Terminal device, TWAG, ePDG, and PGW

ABSTRACT

Provided are a communications control method, etc., for multi-access PDN connection establishment requests from terminal devices. Provided is communication control accompanied with establishment of a multi-access PDN connection or with rejection of establishment of a multi-access PDN connection, based on a response to a PDN connectivity establishment request from a terminal device.

TECHNICAL FIELD

The present invention relates to a terminal device and the like.

BACKGROUND ART

The 3rd Generation Partnership Project (3GPP), which undertakesactivities for standardizing recent mobile communication systems, is inthe process of creating specifications for the Evolved Packet System(EPS), which realizes an all-IP architecture (see NPL 1). The EPS is amobile communication system through which mobile operators and the likeprovide mobile telephone services, and is structured including a corenetwork called the Evolved Packet Core (EPC), an access network based onthe radio communication standard called the Long Term Evolution (LTE),and the like.

Furthermore, in the process of creating specifications for the EPS bythe 3GPP, the Network-based IP Flow Mobility (NBIFOM) has been discussed(see NPL 1). The NBIFOM is a technical item that allows one device tosimultaneously utilize a 3GPP interface and an interface other than the3GPP interface (for example, WLAN).

In the related art, one PDN connection accommodates a communicationpath, a bearer, or a transfer path through either a 3GPP access network(for example, LTE access network) or a non-3GPP access network (forexample, WLAN access network).

With the NBIFOM, a state can be maintained in which one PDN connectionsimultaneously accommodates a bearer, a communication path, or atransfer path through the 3GPP access network and a bearer, acommunication path, or a transfer path through the non-3GPP accessnetwork. Such a PDN connection is defined as a multi-access PDNconnection.

It has also been discussed for the NBIFOM to stipulate an operation modeindicating an endpoint node that is capable of initiating switching of acommunication path. Specifically, it has been discussed for the NBIFOMto classify an operation mode into a UE-initiated mode and aNetwork-initiated mode.

A terminal device and each device included in a core network and anaccess network are capable of transmitting/receiving data on acommunication path through an appropriate access network for eachapplication by using an NBIFOM function.

Furthermore, an endpoint node configured to initiate switching a flow ofthe multi-access PDN connection established by using the NBIFOM functioncan be configured based on the operation mode.

CITATION LIST Non Patent Literature

-   NPL 1: 3GPP TR 23.861 Technical Specification Group Services and    System Aspects, Network-based IP Flow Mobility (Release 13)

SUMMARY OF INVENTION Technical Problem

For the NBIFOM, a detailed procedure for establishing a multi-access PDNconnection has not been stipulated. Specifically, details of successfulprocedure and failure procedure in the multi-access PDN connectivityestablishment procedure have not been stipulated.

More specifically, details of accept means and reject procedure from anetwork for a request of establishing the multi-access PDN connection inwhich a terminal device supports an NBIFOM function, have not beenclarified.

In light of the foregoing, an object of the present invention is toprovide a suitable way of implementing a communication control procedurein response to a PDN connectivity establishment request from a terminaldevice or the like.

Solution to Problem

To address the above issues, a terminal device of the present inventionincludes a WLAN interface unit configured to receive a Packet DataNetwork (PDN) Connectivity Accept message from a Trusted WLAN AccessGateway (TWAG) in order to establish a PDN connection. The PDNConnectivity Accept message includes information indicating aNetwork-based IP Flow Mobility (NBIFOM) mode.

A Trusted WLAN Access Gateway (TWAG) of the present invention includesan IP mobile communication network interface unit configured to transmita Packet Data Network (PDN) Connectivity Accept message to a terminaldevice. The PDN Connectivity Accept message includes informationindicating a Network-based IP Flow Mobility (NBIFOM) mode.

A terminal device of the present invention includes a WLAN interfaceunit configured to receive an authentication response message from anenhanced Packet Data Gateway (ePDG) in order to establish a Packet DataNetwork (PDN) connection. The authentication response message includesinformation indicating a Network-based IP Flow Mobility (NBIFOM) mode.

An enhanced Packet Data Gateway (ePDG) of the present invention includesan IP mobile communication network interface unit configured to transmitan authentication response message to a terminal device. Theauthentication response message includes information indicating aNetwork-based IP Flow Mobility (NBIFOM) mode.

A PDN Gateway (PGW) of the present invention includes an IP mobilecommunication network interface unit configured to transmit a CreateSession Request message to a Trusted WLAN Access Gateway (TWAG) or anenhanced Packet Data Gateway (ePDG). The Create Session Request messageincludes information indicating a Network-based IP Flow Mobility(NBIFOM) mode.

Advantageous Effects of Invention

The present invention enables a communication control procedureaccompanied with a multi-access PDN connectivity establishment requestfrom a terminal device to be implemented.

Specifically, according to the present invention, a successful procedurein establishing a multi-access PDN connection and/or a failure procedurein establishing the multi-access PDN connection can be supported.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem.

FIGS. 2A and 2B are diagrams illustrating a configuration of an IPmobile communication network, and the like.

FIG. 3 is a diagram illustrating a functional configuration of a TWAG.

FIGS. 4A to 4E are diagrams illustrating a configuration of a storage ofthe TWAG.

FIG. 5 is a diagram illustrating a functional configuration of an HSS.

FIGS. 6A and 6B are diagrams illustrating a configuration of a storageof the HSS.

FIG. 7 is a diagram illustrating a functional configuration of a UE.

FIGS. 8A to 8E are diagrams illustrating a configuration of a storage ofthe UE.

FIG. 9 is a diagram illustrating a functional configuration of a PGW.

FIGS. 10A to 10E are diagrams illustrating a configuration of a storageof the PGW.

FIG. 11 is a diagram illustrating a functional configuration of a PCRF.

FIGS. 12A to 12E are diagrams illustrating a configuration of a storageof the PCRF.

FIG. 13 is a diagram illustrating a state from a first initial state toa state after a PDN connectivity procedure is completed.

FIG. 14 is a diagram illustrating a state from a second initial state toa state after the PDN connectivity procedure is completed.

FIG. 15 is a diagram illustrating a procedure for leading to an initialstate.

FIG. 16 is a diagram illustrating a first PDN connectivity procedure.

FIG. 17 is a diagram illustrating a first additional attach procedure.

FIG. 18 is a diagram illustrating a PDN connectivity procedure.

DESCRIPTION OF EMBODIMENTS 1. First Embodiment

Hereinafter, a radio communication technology according to an embodimentof the present invention will be described in detail with reference tothe drawings.

1.1. System Overview

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem according to the present embodiment. As illustrated in FIG. 1, amobile communication system 9 is constituted of a mobile terminal deviceUE 10, an LTE base station eNB 45 included in an access network A, aTrusted WLAN Access Gateway (gateway TWAG) 74 included in an accessnetwork B, a Mobility Management Entity (MME) 40 included in a corenetwork 90, a Serving Gateway (SGW) 35, and a PDN Gateway (PGW) 30.

Here, the UE 10 may be any mobile terminal device, and may be a Userequipment (UE), a Mobile equipment (ME), or a Mobile Station (MS).

Furthermore, the access network A may be an LTE access network, and theeNB 45 included in the access network A may be an LTE radio basestation. Note that the access network A may include multiple radio basestations.

Furthermore, the access network B may be a WLAN access network. The TWAG74 may be a gateway that connects to the PGW 30 in the core network 90to connect the core network 90 and the WLAN access network.

In the present embodiment, the UE 10 can establish a PDN connectionusing an EPS bearer through the access network A.

Furthermore, the UE 10 can establish a PDN connection by using aGTP/PMIPv6 transfer path between the PGW 30 and the UE 10. Note that thetransfer path may be a bearer.

Here, the core network 90 refers to an IP mobile communication networkrun by a mobile operator.

For example, the core network 90 may be a core network 90 for the mobileoperator that runs and manages the mobile communication system 9, or maybe a core network 90 for a virtual mobile operator such as a MobileVirtual Network Operator (MVNO).

The MME 40 is a control device configured to perform, through the accessnetwork A, location management and access control of the UE 10. Detailsof the MME 40 will be descried later.

Furthermore, the SGW 35 is a gateway device between the core network 90and the access network A, and is configured to transfer user databetween the UE 10 and the PGW 30.

The PGW 30 is a gateway device of a packet data service network (PacketData Network (PDN)) that provides a communication service to the UE 10.

In the present embodiment, the UE 10 can establish a first PDNconnection and/or a second PDN connection.

Furthermore, in the present embodiment, the NBIFOM is a technology thatallows establishment of a multi-access PDN connection.

Furthermore, in the present embodiment, the multi-access PDN connectionrefers to a PDN connection capable of accommodating, in one PDNconnection, a transfer path and/or a bearer over 3GPP access and/or WLANaccess. In other words, the multi-access PDN connection can accommodateboth a transfer path through the 3GPP access and a transfer path throughthe WLAN access. Note that the multi-access PDN connection may be a PDNconnection accommodating only a bearer through the 3GPP access or may bea PDN connection accommodating only a transfer path through the WLANaccess. In other words, the multi-access PDN connection refers to a PDNconnection capable of constituting one or multiple transfer paths.

In the present embodiment, to clearly distinguish from a PDN connectionestablished based on an IP Flow Mobility (IFOM), a PDN connection inwhich a transfer path of a specific flow can be selected based on theNBIFOM is defined as “multi-access PDN connection”.

Note that the IFOM is a technology for switching a communication path ofa specific IP flow by using a Dual Stack Mobile IPv6 (DSMIPv6) protocol,and in the present embodiment, a PDN connection capable of switching,based on the IFOM, a communication path of a specific IP flow isdescribed as a PDN connection for the IFOM.

Furthermore, the first PDN connection may be the above-describedmulti-access PDN connection.

In detail, the first PDN connection is a PDN connection in which, as onePDN connection, a communication path EPS bearer through the accessnetwork A and a communication path constituted of a GTP/PMIPv6 tunnelthrough the access network B can be used. That is, this PDN connectioncan transmit/receive data through the 3GPP access, the WLAN access, orboth thereof. The first PDN connection may be the multi-access PDNconnection.

Furthermore, the second PDN connection may be the PDN connection of therelated art, rather than the multi-access PDN connection. Note that thesecond PDN connection may be a single-access PDN connection.

Here, the single-access PDN connection refers to one PDN connectionconstituted of only a transfer path through either the 3GPP access orthe WLAN access, unlike the multi-access PDN connection. In detail, thesingle-access PDN connection refers to a PDN connection established bythe attach of the related art.

That is, the second PDN connection is a PDN connection constituted ofthe EPS bearer through the access network A or a PDN connectionconstituted of the GTP/PMIPv6 transfer path through the access networkB. The second PDN connection accommodates a transfer path and/or acommunication path through either one of the access networks.

As described above, the single-access PDN connection refers to a PDNconnection that is different from the multi-access PDN connection andthe PDN connection for the IFOM. Moreover, the single-access PDNconnection refers to a PDN connection that is also different from a PDNconnection for a Local IP Access (LIPA). Here, the LIPA refers tocommunication control for performing offload to a home network. Morespecifically, the base station to which the terminal device connectsperforms the offload by transmitting, to a home network to which thebase station connects, user data that is conventionally delivered viathe core network 90. The PDN connection for LIPA refers to a PDNconnection for such communication based on the LIPA.

Next, an example of a configuration of the core network 90 will bedescribed. FIG. 2A illustrates an example of a configuration of the IPmobile communication network. As illustrated in FIG. 2A, the corenetwork 90 is constituted of a Home Subscriber Server (HSS) 50, anAuthentication, Authorization, Accounting (AAA) 55, a Policy andCharging Rules Function (PCRF) 60, the PGW 30, an enhanced Packet DataGateway (ePDG) 65, the SGW 35, the MME 40, and a Serving GPRS SupportNode (SGSN) 45.

Furthermore, the core network 90 is capable of connecting to multipleradio access networks (an LTE AN 80, a WLAN ANb 75, a WLAN ANa 70, aUTRAN 20, and a GERAN 25).

Such a radio access network may be constituted of multiple differentaccess networks, or may be constituted of either one of the accessnetworks. Moreover, the UE 10 can wirelessly connect to the radio accessnetwork.

Moreover, a WLAN access network b (WLAN ANb 75) that connects to thecore network 90 via the ePDG 65 and a WLAN access network a (WLAN ANa75) that connects to the PGW 30, the PCRF 60, and the AAA 55 can beconfigured as access networks connectable in a WLAN access system. Notethat each device has a similar configuration to those of the devices ofthe related art in a mobile communication system using EPS, and thusdetailed descriptions thereof will be omitted. Each device will bedescribed briefly hereinafter.

The PGW 30 is connected to the PDN 100, the SGW 35, the ePDG 65, theWLAN ANa 70, the PCRF 60, and the AAA 55 and is a relay deviceconfigured to transfer user data by functioning as a gateway devicebetween the PDN 100 and the core network 90.

The SGW 35 is connected to the PGW 30, the MME 40, the LTE AN 80, theSGSN 45, and the UTRAN 20 and is a relay device configured to transferuser data by functioning as a gateway device between the core network 90and the 3GPP access network (the UTRAN 20, the GERAN 25, and the LTE AN80).

The MME 40 is connected to the SGW 35, the LTE AN 80, and the HSS 50 andis an access control device configured to perform location informationmanagement and access control for the UE 10 via the LTE AN 80.Furthermore, the core network 90 may include multiple locationmanagement devices. For example, a location management device differentfrom the MME 40 may be constituted. The location management devicedifferent from the MME 40 may be connected to the SGW 35, the LTE AN 80,and the HSS 50, as with the MME 40.

Furthermore, when multiple MMEs 40 are included in the core network 90,the MMEs 40 may be connected to each other. With this configuration, thecontext of the UE 10 may be transmitted/received among the MMEs 40.

The HSS 50 is connected to the MME 40 and the AAA 55 and is a managingnode configured to manage subscriber information. The subscriberinformation of the HSS 50 is referenced during access control for theMME 40, for example. Moreover, the HSS 50 may be connected to thelocation management device different from the MME 40.

The AAA 55 is connected to the PGW 30, the HSS 50, the PCRF 60, and theWLAN ANa 70 and is configured to perform access control for the UE 10connected via the WLAN ANa 70.

The PCRF 60 is connected to the PGW 30, the WLAN ANa 75, the AAA 55, andthe PDN 100 and is configured to perform QoS management on datadelivery. For example, the PCRF 60 manages QoS of a communication pathbetween the UE 10 and the PDN 100.

The ePDG 65 is connected to the PGW 30 and the WLAN ANb 75 and isconfigured to deliver user data by functioning as a gateway devicebetween the core network 90 and the WLAN ANb 75.

The SGSN 45 is connected to the UTRAN 20, the GERAN 25, and the SGW 35and is a control device for location management between a 3G/2G accessnetwork (UTRAN/GERAN) and the LTE access network (E-UTRAN). In addition,the SGSN 45 has functions of: selecting the PGW 30 and the SGW 35;managing a time zone of the UE 10; and selecting the MME 40 at the timeof handover to the E-UTRAN.

Also, as illustrated in FIG. 2B, each radio access network includesdevices to which the UE 10 is actually connected (for example, a basestation device and an access point device), and the like. The devicesused in these connections are assumed to adapt to the radio accessnetworks.

In the present embodiment, the LTE AN 80 includes the eNB 45. The eNB 45is a radio base station to which the UE 10 connects in an LTE accesssystem, and the LTE AN 80 may include one or multiple radio basestations.

The WLAN ANa 70 includes a WLAN APa 72 and the TWAG 74. The WLAN APa 72is a radio base station to which the UE 10 connects in a WLAN accesssystem trusted by the operator running the core network 90, and the WLANANa 70 may include one or multiple radio base stations. The GW 74 is agateway device between the core network 90 and the WLAN ANa 70.Furthermore, the WLAN APa 72 and the GW 74 may be constituted as asingle device.

Even in a case where the operator running the core network 90 and theoperator running the WLAN ANa 70 are different, such a configuration canbe implemented through contracts and agreements between the operators.

Furthermore, the WLAN ANb 75 includes a WLAN APb 76. The WLAN APb 76 isa radio base station to which the UE 10 connects in the WLAN accesssystem in a case where no trusting relationship is established with theoperator running the core network 90, and the WLAN ANb 75 may includeone or multiple radio base stations.

In this manner, the WLAN ANb 75 is connected to the core network 90 viathe ePDG 65, which is a device included in the core network 90, servingas a gateway. The ePDG 65 has a security function for ensuring thesecurity of communication.

The UTRAN 20 includes a Radio Network Controller (RNC) 24 and an eNB(UTRAN) 22. The eNB (UTRAN) 22 is a radio base station to which the UE10 connects through a UMTS Terrestrial Radio Access (UTRA), and theUTRAN 20 may include one or multiple radio base stations. Furthermore,the RNC 24 is a control unit configured to connect the core network 90and the eNB (UTRAN) 22, and the UTRAN 20 may include one or multipleRNCs. Moreover, the RNC 24 may be connected to one or multiple eNBs(UTRANs) 22. In addition, the RNC 24 may be connected to a radio basestation (Base Station Subsystem (BSS) 26) included in the GERAN 25.

The GERAN 25 includes the BSS 26. The BSS 26 is a radio base station towhich the UE 10 connects through GSM/EDGE Radio Access (GERA), and theGERAN 25 may be constituted of one or multiple radio base station BSSs.Furthermore, the multiple BSSs may be connected to each other. Moreover,the BSS 26 may be connected to the RNC 24.

Note that in the present specification, the UE 10 being connected toradio access networks refers to the UE 10 being connected to a basestation device, an access point, or the like included in each radioaccess network, and data, signals, and the like beingtransmitted/received also pass through those base station devices,access points, or the like.

1.2. Device Configuration

The configuration of each device will be described below.

1.2.1. TWAG Configuration

FIG. 3 illustrates a device configuration of the TWAG 74. As illustratedin FIG. 3, the TWAG 74 is constituted of an IP mobile communicationnetwork interface unit 320, a control unit 300, and a storage 340. TheIP mobile communication network interface unit 320 and the storage 340are connected to the control unit 300 via a bus.

The control unit 300 is a function unit for controlling the TWAG 74. Thecontrol unit 300 implements various processes by reading out andexecuting various programs stored in the storage 340.

The IP mobile communication network interface unit 320 is a functionunit through which the TWAG 74 is connected to the PGW 30.

The storage 340 is a function unit for storing programs, data, and thelike necessary for each operation of the TWAG 74. The storage 340 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 3, the storage 340 stores a TWAG capability 342,a Network capability 344, and an EPS bearer context 346. Hereinafter,information elements stored in the storage 340 will be described.

FIGS. 4A to 4E illustrate the information elements stored in the storage340. FIG. 4A illustrates an example of the TWAG capability stored by theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether or not capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether or not the TWAG 74 supports an NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”. Note thatthe NBIFOM function may be information indicating the possession of thefunction of establishing the multi-access PDN connection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 4A, the NBIFOM capability may be stored whilebeing associated with a TWAG ID which is the identification informationon the TWAG 74. If not associated with the TWAG ID, the NBIFOMcapability may mean capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored while beingassociated with each other, the TWAG 74 may store the TWAG capability ofmultiple TWAGs 74.

In this case, when the UE 10 performs a handover to another TWAG 74, theTWAG 74 may select a TWAG 74 to which the handover is made, based on theTWAG capability.

Next, the Network capability 344 will be described. FIG. 4B illustratesan example of the Network capability stored by the TWAG 74. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. In other words, the identificationinformation indicates whether or not the PGW 30 supports the NBIFOMfunction. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”. Note that the NBIFOM function may beinformation indicating the possession of the function of establishingthe multi-access PDN connection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

As illustrated in FIG. 4B, the TWAG 74 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 4B, theNBIFOM capability may be stored associated with each of the multiplePGWs 30. The PGW ID may be any information for identifying the PGW 30,and may be an Access Point Name (APN), for example.

Next, the EPS bearer context will be described. The EPS bearer contextmay be classified into an EPS bearer context for each UE 10 stored foreach UE 10, an EPS bearer context for each PDN connection, and an EPSbearer context for each bearer and/or transfer path.

FIG. 4C illustrates information elements included in the EPS bearercontext for each UE 10. As is obvious from FIG. 4C, the TWAG 74 stores,for each UE 10, a UE NBIFOM capability and an NBIFOM allowed.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information indicating whether or not the UE 10 supportsthe NBIFOM function. More specifically, for example, the UE NBIFOMcapability may include “allowed” or “Not allowed”. Note that the NBIFOMfunction may be information indicating the possession of the function ofestablishing the multi-access PDN connection.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection. In other words, in the present embodiment, the UE 10 isallowed to establish the multi-access PDN connection by using the APN 1.Note that the APN 1 is also allowed to establish the PDN connection ofthe related art, rather than the multi-access PDN connection.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection. That is, in thepresent embodiment, the UE 10 cannot establish the multi-access PDNconnection by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished. The TWAG 74 may access the HSS 50 to acquire the NBIFOMallowed before the PDN connection is established and/or during theestablishment procedure. Furthermore, the EPS bearer context for each UE10 may include identification information on the UE 10. Theidentification information on the UE 10 may be an IMSI.

Furthermore, FIG. 4D illustrates the EPS bearer context for each PDNconnection. The EPS bearer context for each PDN connection includes aPDN connection ID, a Network allowed mode, an Operation mode, a Userplane connection ID, a TWAG MAC address, and an NBIFOM Permission.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the PDN connection is the first PDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be a UE initiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The User plane connection ID is identification information foridentifying a connection used for transmission of user data when the UE10 establishes a transfer path via the TWAG 74. The TWAG MAC address isa physical address of the TWAG 74.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection. In other words, theNBIFOM permission indicates that the first PDN connection hasestablished. That is, the fact that the TWAG 74 has stored the NBIFOMpermission means that this PDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored bythe TWAG 74 upon the PDN connection being established. The TWAG 74 mayaccess the HSS 50 to acquire the NBIFOM permission during theestablishment of the PDN connection. Alternatively, the TWAG 74 maystore the NBIFOM Permission, based on the fact that the multi-access PDNconnection has been established.

Next, the EPS bearer context for each bearer and/or transfer path willbe described. As illustrated in FIG. 4E, the EPS bearer context for eachbearer and/or transfer path may include transfer path identificationinformation and a Routing Rule. The transfer path identificationinformation is information for identifying a transfer path and/orbearer. The transfer path identification information may be an EPSbearer ID, for example.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Based on this association,whether using a communication path through the 3GPP access network orusing a communication path through the WLAN access network isdetermined.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60, or maybe notified from the UE 10. Alternatively, the Routing rule may be avalue that the TWAG 74 prestores as a default value.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the flow can be switched for each application. Alternatively,the Routing Filter may include the TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule. The TWAG capability and the Networkcapability may be included in the EPS bearer context.

1.2.2. HSS Configuration

Next, the configuration of the HSS 50 will be described. FIG. 5illustrates a device configuration of the HSS 50. As illustrated in FIG.5, the HSS 50 is constituted of an IP mobile communication networkinterface unit 520, a control unit 500, and a storage 540. The IP mobilecommunication network interface unit 520 and the storage 540 areconnected to the control unit 500 via a bus.

The control unit 500 is a function unit for controlling the HSS 50. Thecontrol unit 500 implements various processes by reading out andexecuting various programs stored in the storage 540.

The IP mobile communication network interface unit 520 is a functionunit through which the HSS 50 is connected to the MME 40 and/or anotherMME 40, and the AAA 55.

The storage 540 is a function unit for storing programs, data, and thelike necessary for each operation of the HSS 50. The storage 540 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 5, the storage 540 stores HSS data 542.Hereinafter, information elements stored in the storage 540 will bedescribed. FIGS. 6A and 6B illustrate the information elements stored inthe storage 540. FIG. 6A illustrates an example of HSS data for each UE10 stored by the HSS 50.

As illustrated in FIG. 6A, the HSS data for each UE 10 includes an IMSI,an MSISDN, an IMEI/IMEISV, an Access Restriction, a UE NBIFOMcapability, and an NBIFOM allowed. The IMSI is identificationinformation assigned to a user (subscriber) using the UE 10. The MSISDNrepresents the phone number of the UE 10. The IMEI/IMISV isidentification information assigned to the UE 10. The Access Restrictionindicates registration information for access restriction.

The UE NBIFOM capability indicates the NBIFOM capability of the UE 10.The UE NBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capabilityindicates whether or not the UE 10 supports the NBIFOM function. Morespecifically, for example, the NBIFOM capability may include “allowed”or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection. In other words, in the present embodiment, the UE 10 isallowed to establish the multi-access PDN connection by using the APN 1.Note that the APN 1 is also allowed to establish the PDN connection ofthe related art, rather than the multi-access PDN connection.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection. That is, in thepresent embodiment, the UE 10 cannot establish the multi-access PDNconnection by using the APN 2. The NBIFOM allowed may be stored beforethe PDN connection is established.

FIG. 6B illustrates an example of HSS data for each PDN connectionstored by the HSS 50. As is obvious from FIG. 6B, the HSS data for eachPDN connection includes at least a Context ID, a PDN address, a PDNType, an Access Point Name (APN), a WLAN offload ability, a PDN GW ID,and an NBIFOM Permission.

The Context ID is identification information on the context storing theHSS data for each PDN connection. The PDN Address represents aregistered IP address. The PDN Address is an IP address of the UE 10.The PDN Type indicates the type of PDN Address. That is, the PDN Type isidentification information for identifying IPv4, IPv6, or IPv4v6, forexample. The APN is a label indicating an access destination in thenetwork, in accordance with DNS naming convention.

The WLAN offload ability is identification information indicatingwhether traffic connected through this APN can perform offload to theWLAN by utilizing a cooperative function between the WLAN and the 3GPP,or maintains the 3GPP connection. The WLAN offload ability may vary foreach RAT type. Specifically, the LTE (E-UTRA) and the 3G (UTRA) may havedifferent WLAN offload ability.

The PDN GW identity is identification information for identifying thePGW 30 utilized in this APN. This identification information may be aFully Qualified Domain Name (FQDN) or an IP address.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection. In other words, theNBIFOM permission indicates that the first PDN connection has beenestablished. That is, the fact that the TWAG 74 has stored the NBIFOMpermission means that this PDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored bythe TWAG 74 upon the PDN connection being established.

Specifically, for example, the HSS data for each PDN connectionincluding the APN 1 may include the NBIFOM Permission, and the HSS datafor each PDN connection including the APN 2 need not include the NBIFOMPermission.

In other words, the PDN connection based on the APN 1 may be the firstPDN connection, and the PDN connection based on the APN 2 cannot be thefirst PDN connection.

1.2.3. UE Configuration

Next, the configuration of the UE 10 will be described. FIG. 7illustrates a device configuration of the UE 10. As illustrated in FIG.7, the UE 10 is constituted of an LTE interface unit 720, a WLANinterface unit 740, a control unit 700, and a storage 750.

The LTE interface unit 720, the WLAN interface unit 740, and the storage750 are connected to the control unit 700 via a bus.

The control unit 700 is a function unit for controlling the UE 10. Thecontrol unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The LTE interface unit 720 is a function unit through which the UE 10connects to an IP access network via an LTE base station. Furthermore,an external antenna 710 is connected to the LTE interface unit 720.

The WLAN interface unit 740 is a function unit through which the UE 10connects to the IP access network via a WLAN AP. Furthermore, anexternal antenna 730 is connected to the WLAN interface unit 740.

The control unit 700 is a function unit for controlling the UE 10. Thecontrol unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The storage 750 is a function unit for storing programs, data, and thelike necessary for each operation of the UE 10. The storage 750 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 7, the storage 750 stores a UE context 752.Hereinafter, information elements stored in the storage 750 will bedescribed. Note that the UE context 752 is classified into a UE contextfor each UE 10, a UE context for each PDN connection, and a UE contextfor each transfer path and/or bearer.

FIG. 8A is an example of the UE context stored for each UE 10. Asillustrated in FIG. 8A, the UE context for each UE 10 includes an IMSI,an EMM State, a GUTI, an ME Identity, and a UE NBIFOM capability.

The IMSI is identification information assigned to a user (subscriber)using the UE 10.

The EMM State indicates a mobility management state of the UE 10. Forexample, the EMM State may be EMM-REGISTERED in which the UE 10 isregistered with the network (registered state) or EMM-DEREGISTERED inwhich the UE 10 is not registered with the network (deregistered state).

The GUTI is an abbreviation of “Globally Unique Temporary Identity”, andis temporary identification information on the UE 10. The GUTI isconstituted of identification information on the MME 40 (Globally UniqueMME Identifier (GUMMEI)) and identification information on the UE 10 ina specific MME 40 (M-TMSI). The ME identity is an ID of an ME, and maybe the IMEI/IMISV, for example.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information for each UE 10 indicating whether or not theNBIFOM function is supported. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”. Note that the NBIFOMfunction may be information indicating the possession of the function ofestablishing the multi-access PDN connection.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has capability of establishing thefirst PDN connection. That is, the existence of the UE NBIFOM capabilityin the storage of the UE 10 may mean that the UE 10 has the function ofestablishing the first PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage of the UE10 may mean that the UE 10 supports the NBIFOM function.

FIG. 8B illustrates an example of the UE context for each PDNconnection. As illustrated in FIG. 8B, the UE context for each PDNconnection includes at least a PDN connection ID, an APN in Use, an IPaddress, a Default Bearer, a WLAN offload ability, a UE allowed mode,and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information. The APN in Use is an APN utilized bythe UE 10 most recently. This APN may be constituted of identificationinformation on the network and identification information on a defaultoperator. The IP Address is an IP address assigned to the UE 10 for thePDN connection, and may be an IPv4 address or an IPv6 prefix.

The Default Bearer is EPS bearer identification information foridentifying a default bearer in this PDN connection.

The WLAN offloadability is WLAN offload permission informationindicating whether or not to allow a communication associated with thePDN connection to perform offload to the WLAN by using an interworkingfunction between the WLAN and the 3GPP, or whether or not to maintainthe 3GPP access.

The UE allowed mode is an Operation mode allowed by the UE 10. Thisidentification information may indicate the UE initiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the PDN connection is the first PDN connection.

FIG. 8C illustrates the UE context for each bearer. The UE context foreach bearer includes transfer path identification information and aRouting Rule. The transfer path identification information isinformation for identifying a transfer path and/or bearer. The transferpath identification information may be an EPS bearer ID, for example.Furthermore, the transfer path identification information may beassociated with the TFT.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN. Furthermore, the Routing address indicates an IP addressthrough which the flow can pass. For example, the Routing address may bean IP address of the SGW 35. Alternatively, the Routing address may bean IP address of the TWAG 74. Alternatively, the Routing address may bean IP address of a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the UE 10 can switch the flow for each application.Alternatively, the Routing Filter may include a TFT.

The Routing Rule may store multiple rules (regulations). Furthermore,the Routing Rule may include priority for each rule.

FIG. 8D illustrates the TWAG capability. The TWAG capability storesidentification information (NBIFOM capability) indicating whether or notcapability of establishing the first PDN connection is supported foreach TWAG 74. In other words, the identification information indicateswhether or not the TWAG 74 supports the NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”. Note thatthe NBIFOM function may be information indicating the possession of thefunction of establishing the multi-access PDN connection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The UE 10 may store the NBIFOM capability associated with the TWAG ID.Furthermore, the NBIFOM capability of multiple TWAGs 74 may be stored.

FIG. 8E illustrates an example of the Network capability. In the Networkcapability, the NBIFOM capability is stored for each network, i.e., foreach PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 8E, the TWAG 74 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 8E, theNBIFOM capability may be stored associated with each of the multiplePGWs 30.

The PGW ID is information for identifying the PGW 30. The PGW ID may bean APN, for example.

The TWAG capability and the Network capability may be included in the UEcontext, or may be information separated from the UE context.

That is, the UE 10 may store the TWAG capability and the Networkcapability included in the UE context, or may store the TWAG capabilityand the Network capability separately from the UE context.

1.2.4. PGW Components

Next, the components of the PGW 30 will be described. FIG. 9 illustratesa device configuration of the PGW 30. As illustrated in FIG. 9, the PGW30 is constituted of an IP mobile communication network interface unit920, a control unit 900, and a storage 940. The IP mobile communicationnetwork interface unit 920 and the storage 940 are connected to thecontrol unit 900 via a bus.

The control unit 900 is a function unit for controlling the PGW 30. Thecontrol unit 900 implements various processes by reading out andexecuting various programs stored in the storage 940.

The IP mobile communication network interface unit 920 is a functionunit through which the PGW 30 is connected to the SGW 35 and/or the PCRF60 and/or the ePDG 65 and/or the AAA 55 and/or the GW 74.

The storage 940 is a function unit for storing programs, data, and thelike necessary for each operation of the PGW 30. The storage 940 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 9, the storage 940 stores an EPS bearer context942. Note that the EPS bearer context includes an EPS bearer contextstored for each UE 10, an EPS bearer context stored for each APN, an EPSbearer context stored for each PDN connection, and an EPS bearer contextstored for each transfer path and/or bearer.

First, the EPS bearer context for each UE 10 will be described. FIG. 10Aillustrates an example of the EPS bearer context for each UE 10. Asillustrated in FIG. 10A, the EPS bearer context includes at least anIMSI, an ME identity, an MSISDN, and a UE NBIFOM capability. The IMSI isinformation for identifying a user of the UE 10. The ME identity is anID of an ME, and may be the IMEI/IMISV, for example. The MSISDNrepresents the phone number of the UE 10.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information indicating whether ornot each UE 10 has capability of establishing the first PDN connection.More specifically, for example, the NBIFOM capability may include“allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

Next, the EPS bearer context for each PDN connection will be described.FIG. 10B illustrates an example of the EPS bearer context for each PDNconnection.

As illustrated in FIG. 10B, the context includes at least a PDNconnection ID, an IP address, a PDN type, an APN, a Network allowedmode, and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The IP Address indicates an IP address assigned to the UE 10 for thisPDN connection. The IP address may be an IPv4 and/or an IPv6 prefix.

The PDN type indicates the type of the IP address. The PDN typeindicates IPv4, IPv6 or IPv4v6, for example.

The APN is a label indicating an access destination in the network, inaccordance with DNS naming convention.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the current PDN connection is the first PDN connection.

More specifically, for example, the UE initiated mode in which the UE 10is allowed to initiate the communication control or the Networkinitiated mode in which the network is allowed to initiate thecommunication control may be identified.

Next, an example of the EPS bearer context for each transfer path and/orbearer will be described with reference to FIG. 10C. As illustrated inFIG. 10C, the context includes at least transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.Furthermore, the transfer path identification information may beassociated with the TFT.

The Routing access type indicates an access network through which theflow passes. For example, the Routing access type indicates the 3GPP orthe WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof the Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The Routing Filter may include an IP header so that the PGW 30 canswitch the IP flow. Alternatively, the Routing Filter may include anapplication ID so that the PGW 30 can switch the flow for eachapplication. Alternatively, the Routing Filter may include a TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule.

FIG. 10D illustrates the TWAG capability. The TWAG capability storesidentification information (NBIFOM capability) indicating whether or notcapability of establishing the first PDN connection is supported foreach TWAG 74. In other words, the identification information indicateswhether or not the TWAG 74 supports the NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The PGW 30 may store the NBIFOM capability associated with the TWAG ID.

FIG. 10E illustrates an example of the Network capability. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 10E, the PGW 30 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 10E, theNBIFOM capability may be stored associated with each of the multiplePGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean APN, for example.

The TWAG capability and the Network capability may be included in theEPS bearer context, or may be information separated from the UE context.

1.2.5. PCRF Components

Next, the components of the PCRF 60 will be described. FIG. 11illustrates a device configuration of the PCRF 60. As illustrated inFIG. 11, the PCRF 60 is constituted of an IP mobile communicationnetwork interface unit 1120, a control unit 1100, and a storage 1140.The IP mobile communication network interface unit 1120 and the storage1140 are connected to the control unit 1100 via a bus.

The control unit 1100 is a function unit for controlling the PCRF 60.The control unit 1100 implements various processes by reading out andexecuting various programs stored in the storage 1140.

The IP mobile communication network interface unit 1120 is a functionunit through which the PCRF 60 is connected to the PGW 30 and/or theTWAG 74 and/or the AAA 55.

The storage 1140 is a function unit for storing programs, data, and thelike necessary for each operation of the PCRF 60. The storage 940 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 11, the storage 1140 stores UE context 1142. Notethat the UE context may be classified into a UE context stored for eachUE 10 and a UE context stored for each PDN connection.

FIG. 12A illustrates the UE context for each UE 10. As illustrated inFIG. 12A, the context includes at least a Subscriber ID and a UE NBIFOMcapability. The Subscriber ID is identification information on a user.For example, the Subscriber ID may be an IMSI.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information indicating whether or not the UE 10 supportsthe NBIFOM function. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Next, the UE context for each PDN connection will be described. FIG. 12Billustrates an example of the UE context for each PDN connection. Asillustrated in FIG. 12B, the context may include at least an APN, anOperation mode, a Network Policy, a Charging Rule, a PCC Rule, and a QoSRule.

The APN is a label indicating an access destination in the network, inaccordance with DNS naming convention. The Operation mode isidentification information on a mode indicating which of the UE 10 andthe network takes an initiative in transmitting/receiving data or isallowed to initiate communication control when the PDN connection is thefirst PDN connection. More specifically, for example, an Operation modein which the UE 10 is allowed to initiate the communication control maybe the UE initiated mode.

Furthermore, an Operation mode in which the network and/or the PGW 30and/or the PCRF 60 is allowed to initiate the communication control maybe the Network initiated mode.

The Network Policy is a communication control policy on the networkside, and may include the Network allowed mode. Alternatively, the PCRF60 may store the Network allowed mode separately from the NetworkPolicy.

The Charging Rule is a regulation on charging. In accordance with theCharging Rule determined by the PCRF 60, a PCEF performs charging.

The PCC Rule is a regulation relating to control of the Network Policyand Charging Rule. In accordance with the PCC Rule, the PCEF performscommunication control and charging. The QoS Rule is a regulationrelating to QoS of the flow. The QoS Rule may be associated with the PCCRule.

FIG. 12C illustrates the UE context for each transfer path and/orbearer. As illustrated in FIG. 12C, the UE context for each transferpath and/or bearer includes at least a Routing Rule.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Based on this association,whether using a communication path through the 3GPP access network orusing a transfer path through the WLAN access network is determined.Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the UE 10 and/or the TWAG 74and/or the PGW 30. Alternatively, the Routing Rule may be a value thatthe PCRF 60 prestores as a default value. In this case, the PCRF 60 maydetermine the default value of the Routing Rule in accordance with thePCC Rule.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the flow can be switched for each application. Alternatively,the Routing Filter may include the TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule.

FIG. 12D illustrates an example of the TWAG capability stored by theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether or not capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether or not the TWAG 74 supports the NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 12D, the NBIFOM capability may be stored whilebeing associated with the TWAG ID which is the identificationinformation on the TWAG 74. If not associated with the TWAG ID, theNBIFOM capability may mean the capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored while beingassociated with each other, the PCRF 60 may store the TWAG capability ofmultiple TWAGs 74.

FIG. 12E illustrates an example of the Network capability stored by thePCRF 60. In the Network capability, the NBIFOM capability is stored foreach network, i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. In other words, the identificationinformation indicates whether or not the PGW 30 supports the NBIFOMfunction. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

1.3. Description of Initial State

An initial state in the present embodiment will be described. Theinitial state in the present embodiment may be a first initial state ora second initial state, both of which will be described later. Note thatthe initial state in the present embodiment need not be limited to thefirst or second initial state.

1.3.1. Description of First Initial State

The first initial state will be described. In the first state, the UE 10has not established the first PDN connection with the core network 90.However, the UE 10 has already established the second PDN connection. Ingreater detail, the UE 10 has not established the first PDN connectionwith a PGW_A 1310. However, the UE 10 has established the second PDNconnection with a PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network B.Thus, the second PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_B 1320. Here, thetransfer path may be a bearer.

As described above, in a first state early stage, the UE 10 may be in astate of being connected to the core network 90 via the access networkB.

Note that the UE 10 need not be connected to the core network 90 via theaccess network A. In other words, the UE 10 need not perform an attachthrough the LTE access network.

Alternatively, the UE 10 may be in a state of being connected to thecore network 90 via the access network A. In this case, the UE 10 mayperform an attach procedure initiated by the UE 10 to establish a thirdPDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The first initial state has been described above; however, the firstinitial state is not limited to the above-described state, and onlyneeds to be a state in which the multi-access PDN connection has notbeen established through the access network B, for example.

1.3.2. Description of Procedure for Leading to First Initial State

A procedure for leading to the first initial state will be describedwith reference to FIG. 15. In the procedure for leading to the firstinitial state, at least an attach procedure to the core network 90through the access network B, illustrated in (A) of FIG. 15, isperformed. The first initial state is a state after at least the attachprocedure to the core network 90 through the access network B,illustrated by (A) in FIG. 15, is performed.

Next, details of the attach procedure to the core network 90 through theaccess network B will be described. The UE 10 first performsauthentication procedure for accessing the access network B and the corenetwork 90, and a security association procedure for establishing asecurity association to transmit/receive a message to/from the corenetwork 90 (S1502).

In greater detail, the UE 10 performs an authentication procedure foraccessing the TWAG 74 arranged in the access network B and the PGW 30arranged in the core network 90. Based on the completion of theauthentication procedure, the UE 10 performs a procedure forestablishing security associations between the UE 10 and the TWAG 74 andbetween the TWAG 74 and the PGW 30. In the authentication procedure andthe procedure for establishing a security association, the UE 10 maytransmit, to the core network 90, control information including theAccess Point Name (APN). Furthermore, the authentication procedure andthe procedure for establishing a security association may be performedbased on a technique such as an EAP. The UE 10 can obtain authenticationfor accessing the PGW 30 selected by the TWAG 74 using the APN.

Moreover, the UE 10 may transmit multiple APNs. For example, thetransmission of the APN 1 and the APN 2 will allow the UE 10 to obtain,based on the completion of the authentication procedure and theprocedure for establishing a security association, authentication foraccessing the PGW 30 selected by the TWAG 74 using the APN 1 and the PGW30 selected by the TWAG 74 using the APN 2.

Based on the establishment of the security association, the UE 10performs a PDN connectivity procedure for establishing the second PDNconnection with the core network 90 through the access network B(S1504). In greater detail, the UE 10 establishes, via the TWAG 74, thePDN connection with the PGW_B 1320 arranged in the core network 90.

Specifically, the UE 10 transmits a PDN connectivity request to the TWAG74 and/or the network. The UE 10 may transmit the PDN connectivityrequest including the APN 2.

The TWAG 74 and/or the network receives the PDN connectivity requesttransmitted from the UE 10. Based on the reception of the PDNconnectivity request, the TWAG 74 and/or the network transmits a PDNConnectivity Accept to the UE 10. The TWAG 74 and/or the network maytransmit the PDN Connectivity Accept including the APN 2.

The UE 10 receives the PDN Connectivity Accept transmitted from the TWAG74 and/or the network. Based on the PDN Connectivity Accept, the UE 10transmits a PDN connectivity complete to the TWAG 74 and/or the network.

The TWAG 74 and/or the network receives the PDN connectivity completetransmitted from the UE 10.

1.3.3. Description of Second Initial State

A second initial state will be described. In the second initial state,the UE 10 is in a state of not being connected to the core network 90.In other words, the UE 10 has not established either the first PDNconnection or the second PDN connection with the core network 90. Ingreater detail, the UE 10 has not established the first PDN connectionwith the PGW_A 1310 included and arranged in the core network 90.Furthermore, the UE 10 has not established the second PDN connectionwith the PGW_B 1320 included and arranged in the core network 90.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Furthermore, the selection of gateway using the APN 1 and/or the APN2 may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

As described above, the second initial state may be a state in which theUE 10 has no connection with the core network 90. In other words, the UE10 may be in a state of not being connected to the core network 90through either the access network A or access network B. Thus, the UE 10may be in a state in which the PDN connection has not been established.

The second initial state has been described above; however, the secondinitial state is not limited to the above-described state, and onlyneeds to be a state in which the connection to the core network 90through the access network B has not been established, for example.

1.3.4. Description of Procedure for Leading to Second Initial State

A procedure for leading (transitioning) to the second initial state willbe described with reference to FIG. 15. In the procedure for leading(transitioning) to the second initial state, a state may be employed inwhich the procedure illustrated in (A) of FIG. 15 is not performed. Inother words, the second initial state may be a state in which anyspecial procedure for establishing a connection to the core network 90through the access network B is not performed at all. That is, thesecond initial state may be a state in which the UE 10 initiallyconnects to the core network 90 through the access network B.

1.3.5. Description of Multi-Access PDN Connectivity EstablishmentProcedure

Next, an establishment procedure of the first PDN connection will bedescribed. Here, the initial state may be the first initial state or thesecond initial state. In the present embodiment, after the establishmentof the initial state, the UE 10 performs a PDN connectivity procedurefor establishing the first PDN connection with the core network 90through the access network B (S1506). In greater detail, the UE 10establishes, via the TWAG 74, the first PDN connection with the PGW_A1310 arranged in the core network 90.

Note that the first PDN connection may be constituted of a path that isa combination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As illustrated in FIG. 15, the procedure for establishing the first PDNconnection may be a PDN connectivity procedure using the APN 1. Aspecific example of the PDN connectivity procedure will be describedbelow.

1.4. Examples of PDN Connectivity Procedure

An example of the PDN connectivity procedure for establishing the firstPDN connection will be described with reference to FIG. 16.

1.4.1. Example of First PDN Connectivity Procedure

An example of the first PDN connectivity procedure will be describedwith reference to FIG. 16.

As illustrated in (B) of FIG. 16, the UE 10 first performs theauthentication procedure and the security association procedure forestablishing the security association. Note that the UE 10 may performthe security association procedure when the initial state is the secondinitial state. In other words, the UE 10 need not perform the securityassociation procedure when the initial state is the first initial state.As described above, when the initial state is the first initial state,the UE 10 may omit the security association procedure since the securityassociation has already been established.

Note that the security association procedure performed by the UE 10 maybe similar to the security association procedure described in (A) ofFIG. 15. Therefore, detailed description of the procedure will beomitted.

Next, the UE 10 transmits a PDN connectivity request to the TWAG 74(S2102). The UE 10 may transmit the PDN connectivity request includingat least the PDN connectivity request message ID (PDN connectivityrequest message identity), the procedure transaction ID (Proceduretransaction identity), the request type (Request type), and the PDNtype. Furthermore, the UE 10 may include at least the firstidentification information and/or sixth identification information inthe PDN connectivity request. Moreover, the UE 10 may include the AccessPoint Name (APN) and/or Protocol Configuration Options (PCOs) and/or theTraffic Flow Templates (TFTs) in the PDN connectivity request. Note thatthe UE 10 may transmit the PCO including the first identificationinformation and/or the sixth identification information and/or the TFT.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the possession ofthe function of establishing the multi-access PDN connection.

In addition, the sixth identification information may be a RequestNBIFOM representing that a request to determine the NBIFOM operationmode for the multi-access PDN connection. Additionally/alternatively,the sixth identification information may be information representingthat a request for an NBIFOM operation mode allowed for the multi-accessPDN connection to be established.

As described above, the UE 10 may transmit the PDN connectivity requestincluding the first identification information and/or sixthidentification information to request the establishment of themulti-access PDN connection, without requesting a specific NBIFOMoperation mode.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message. The proceduretransaction ID may be information for identifying the PDN connectivityprocedure.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1in order to establish the multi-access PDN connection. Here, the APN 1may be an APN that is allowed to establish the multi-access PDNconnection and/or an APN that is allowed to perform communication basedon the NBIFOM.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or the sixth identification information.

The TFT may be information for identifying an IP flow that performscommunication by using the PDN connection established in the present PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, by the TFT, user data of a specificapplication can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a specific NBIFOM operation mode,and thus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection without requesting thespecific NBIFOM operation mode, the UE 10 may transmit the PDNconnectivity request without including the TFT. More specifically, whenthe UE 10 includes the first identification information and/or the sixthidentification information, the UE 10 may transmit the PDN connectivityrequest without including the TFT.

Note that in the related art, the UE 10 can perform transmission withinformation indicating the IFOM support included in the PCO. Here, theIFOM support is identification information representing that the IP FlowMobility (IFOM) is supported. Furthermore, the IFOM is a technique forswitching a communication path of a specific IP flow by using the DualStack Mobile IPv6 (DSMIPv6) protocol. Thus, including the informationindicating the IFOM support in the PCO allows the UE 10 to switch theaccess network through which the communication of a specific IP flow isperformed.

In the present embodiment, when the UE 10 includes the firstidentification information and the sixth identification information inthe PCO, the UE 10 does not include the IFOM support. In contrast, whenthe UE 10 includes the IFOM support in the PCO, the UE 10 does notinclude the first identification information and/or the sixthidentification information. As described above, it may be possible tonot configure both the first identification information and/or sixthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 can establish either the PDN connection supporting theIFOM or the PDN connection supporting the NBIFOM, in the establishmentprocedure of a single PDN connection. In other words, the single PDNconnection is any one of the PDN connection supporting the NBIFOM, thePDN connection supporting the IFOM, or the single-access PDN connection.

The TWAG 74 receives the PDN connectivity request transmitted from theUE 10. Based on the reception of the PDN connectivity request and/or thefirst identification information and/or sixth identification informationincluded in the PDN connectivity request, the TWAG 74 transmits a CreateSession Request to the PGW 30 (S2104).

Based on the reception of the PDN connectivity request and/or the firstidentification information and/or sixth identification informationincluded in the PDN connectivity request, the TWAG 74 may transmit theCreate Session Request including at least the first identificationinformation and/or sixth identification information. Furthermore, theTWAG 74 may include the TFT in the Create Session Request, based on thereception of the TFT transmitted from the UE 10.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the PDN connectivityrequest, the TWAG 74 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the TWAG 74 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the TWAG74. Based on the reception of the Create Session Request, and/or thefirst identification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure with the PCRF 60.

Based on the reception of the Create Session Request and/or the firstidentification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure including at least the firstidentification information and/or the sixth identification information.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or TWAG 74.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection or thesingle-access PDN connection, and/or the first identificationinformation, and/or the sixth identification information.

More specifically, when the multi-access PDN connection is to beestablished, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network B, the PDN connection ID, the informationindicating that the PDN connection is the multi-access PDN connection,and the first identification information and/or sixth identificationinformation. Alternatively, when the single-access PDN connection is tobe established, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network B, the PDN connection ID, and theinformation indicating that the PDN connection is the single-access PDNconnection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, based on the reception of the first identificationinformation and/or sixth identification information, the PCRF 60 maytransmit, to the PGW 30, a control message in the IP-CAN session updateprocedure with the PGW 30, the control message including at least theseventh identification information. The detailed description of theseventh identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 transmits aCreate Session Response to the TWAG 74 (S2106).

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 may transmitthe Create Session Response including at least the seventhidentification information.

Furthermore, the PGW 30 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in the Create Session Response.

Note that a method by which the PGW 30 acquires the seventhidentification information is not limited to the above-described methodfor acquiring the seventh identification information from the PCRF 60 inthe IP-CAN session update procedure, and another example may beemployed. For example, the PGW 30 may create the seventh identificationinformation and transmit the Create Session Response including theseventh identification information, without acquiring the seventhidentification information from the PCRF 60 in the IP-CAN session updateprocedure.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection to be established. In other words, theseventh identification information may be an operation mode allowed bythe operator.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode orthe seventh identification information based on the operator policy. Forexample, a policy that allows for the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows for theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows for the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

Based on the Allowed Mode, the PCRF 60 or the PGW 30 may include theallowed operation mode in the seventh identification information. Inother words, when only the Network-Initiated mode is allowed, the PCRF60 or the PGW 30 may include the Network-Initiated mode in the seventhidentification information. Alternatively, when only the UE-Initiatedmode is allowed, the PCRF 60 or the PGW 30 may include the UE-Initiatedmode in the seventh identification information.

Note that when both of the UE-Initiated mode and the Network-Initiatedmode are allowed, the seventh identification information may includeboth the operation modes. Alternatively, when both of the UE-Initiatedmode and the Network-Initiated mode are allowed and a default operationmode is configured, the seventh identification information may includeonly the default operation mode. Note that which of the UE-Initiatedmode and the Network-Initiated mode is defined as the default operationmode may be configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the Requested Operation Mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the TWAG 74 of the seventhidentification information. When none of the operation modes is allowedfor establishment of the PDN connection, the PGW 30 may transmit, to theTWAG 74, the Create Session Response including the cause informationindicating that the Requested Operation Mode is not allowed. When noneof the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the TWAG 74 that there is no allowedoperation.

As described above, based on the Allowed Mode, the PCRF 60 or the PGW 30may regard an operation mode that is allowed for establishment of thePDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theTWAG 74. Thus, in this case, the PGW 30 need not include the TFT in theCreate Session Response.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PGW 30 maytransmit the TFT to the TWAG 74. Thus, in this case, the PGW 30 mayinclude the TFT in the Create Session Response.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the TWAG 74. In other words, the PGW 30 may assign the PDNconnection ID.

The TWAG 74 receives the Create Session Response transmitted from thePGW 30. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the TWAG 74 transmits a PDN Connectivity Accept to the UE 10(S2108).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theTWAG 74 may transmit the PDN Connectivity Accept including at least aPDN Connectivity Accept message ID (PDN Connectivity Accept messageidentity), the procedure transaction ID, the APN, the PDN address (PDNAddress), the PDN connection ID, and the user plane connection ID (UserPlane Connection ID). Furthermore, the TWAG 74 may include at least theseventh identification information in the PDN Connectivity Accept.Moreover, the TWAG 74 may include the PCO and/or a Cause and/or the TFTand/or PDN connection attribute information, in the PDN ConnectivityAccept. Note that the TWAG 74 may transmit the PCO including the seventhidentification information and/or the TFT.

Here, the PDN Connectivity Accept message ID may be a message typerepresenting the PDN Connectivity Accept message.

The APN may be an APN to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection. The TWAG 74 mayinclude the APN 1 in the PDN Connectivity Accept.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The PDN connection ID may be information for uniquely identifying thePDN connection established between the UE 10 and the PGW 30. The PDNconnection ID may be an ID assigned by the PGW 30, or an ID assigned bythe TWAG 74. In other words, the TWAG 74 may assign the PDN connectionID.

The user plane connection ID is information for identifying a userplane. The user plane is a transfer path used for transferring user datain the PDN connection. The TWAG 74 may assign the user plane connectionID.

The Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the TWAG 74 and/or the PGW 30 may include the seventhidentification information in the PCO. However, when the TWAG 74 and/orthe PGW 30 includes the seventh identification information in the PCO,the TWAG 74 and/or the PGW 30 does not include the IFOM support. Incontrast, when the TWAG 74 and/or the PGW 30 includes the IFOM supportin the PCO, the TWAG 74 and/or the PGW 30 does not include the seventhidentification information. As described above, it may be possible tonot configure both the seventh identification information and the IFOMsupport to be effective to ensure a clear distinction between the use ofthe switching of the communication path based on the NBIFOM and the useof the switching of the communication path based on the IFOM.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted/received by using the PDNconnection established in the PDN connectivity procedure is allowed tobe transmitted/received through the access network A and the accessnetwork B, and/or information indicating that the PDN connectionestablished in the present PDN connectivity procedure is themulti-access PDN connection of the operation mode indicated by theseventh identification information when there is only one operation modeindicated by the seventh identification information.

Note that the UE 10 may transmit the PDN Connectivity Accept messagethat further includes the connectivity type indicating the type of thePDN connection and/or the WLAN offload permission information (WLANoffload acceptability) indicating whether or not the WLAN offload can beperformed. Furthermore, the TWAG 74 may transmit the connectivity typeor the WLAN offload permission information including the PDN connectionattribute information.

The UE 10 receives the PDN Connectivity Accept transmitted from the TWAG74. Based on the reception of the PDN Connectivity Accept and/or theseventh identification information included in the PDN ConnectivityAccept, the UE 10 transmits a PDN connectivity complete to the TWAG 74(S2110).

The UE 10 may transmit the PDN connectivity complete including at leastthe PDN connectivity complete message ID (PDN connectivity complete),the procedure transaction ID, and the PDN connection ID.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the PDN connectivity complete. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in thePDN Connectivity Accept, the UE 10 may include the UE-Initiated mode orthe Network-Initiated mode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user. The PDN connectivity complete message ID may be amessage type representing the PDN connectivity complete message.

After the first PDN connectivity procedure is completed, the UE 10 andthe PGW 30 establish the first PDN connection of the operation modedetermined based on the operator policy. Alternatively, the UE 10establishes the first PDN connection of an operation mode selected fromthe operation modes allowed based on the operator policy. Note that theUE 10 may identify the NBIFOM operation mode for the established PDNconnection, based on the reception of the PDN Connectivity Accept,and/or the PDN connection attribute information and/or the seventhidentification information and/or the operation mode selected based onthe seventh identification information. Based on the establishment ofthe first PDN connection, the UE 10 and the PGW 30 determine a PDNconnection and/or a transfer path (such as an EPS bearer) fortransmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT. More specifically, the UE 10 and the PGW 30 transmit/receive aflow identified by of the TFT by using the first PDN connection.

Note that in the example of the first PDN connectivity procedure, a casehas been described in which transmission/reception of the TFT isincluded in the PDN connectivity procedure; however, the first PDNconnectivity procedure is not limited to this case. Thetransmission/reception of the TFT may be performed after themulti-access PDN connection is established.

Therefore, the UE 10 and the TWAG 74 may perform transmission/receptionwithout including the TFT in the PDN connectivity request and/or the PDNconnectivity response (PDN Connectivity Accept), and establish themulti-access PDN connection. In other words, at a point in time when thePDN connection is established, there may be no IP flowtransmitting/receiving user data by using the PDN connection. In thiscase, the UE 10 and the TWAG 74 transmit the TFT after the multi-accessPDN connection is established.

More specifically, when the PDN connection of the UE-Initiated mode isestablished, the UE 10 may transmit the TFT to the TWAG 74. In addition,the TWAG 74 receives the TFT from the UE 10 and transmits the TFT to thePGW 30. Thus, the UE 10 and the PGW 30 can determine a PDN connectionand/or a transfer path (such as an EPS bearer) fortransmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT.

On the other hand, when the PDN connection of the Network-Initiated modeis established, the PGW 30 may transmit the TFT to the TWAG 74. Here,the PGW 30 may receive, from the PCRF 60, the TFT determined based onthe operator policy. In addition, the TWAG 74 receives the TFT from thePGW 30 and transmits the TFT to the UE 10. Thus, the UE 10 and the PGW30 can determine a PDN connection and/or a transfer path (such as an EPSbearer) for transmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT.

Furthermore, in the example of the fourth PDN connectivity procedure, acase has been described in which the UE 10 and the PGW 30 establish thefirst PDN connection of an operation mode selected by the UE 10 from theoperation modes determined based on the operator policy or the operationmodes allowed based on the operator policy; however, the fourth PDNconnectivity procedure is not limited to this case. The UE 10 may rejectthe establishment of the first PDN connection.

For example, when the UE 10 does not support the operation mode allowedbased on the operator policy and/or when the operation mode allowedbased on the operator policy does not comply with the policy of the UE10, the UE 10 may reject the establishment of the first PDN connection.

In greater detail, the UE 10 may transmit a PDN connectivity reject tothe TWAG 74, based on the reception of the PDN Connectivity Acceptand/or the seventh identification information included in the PDNConnectivity Accept and/or the PDN connection attribute informationand/or the policy of the UE 10.

The UE 10 may transmit the PDN connectivity reject including at leastone or more of a PDN connectivity reject message ID (PDN connectivityreject message identity), the procedure transaction ID, and the Cause.Furthermore, the UE 10 may include the fourth identification informationin the PDN connectivity reject. Moreover, the UE 10 may include the PCOand/or the Tw1 value in the PDN connectivity reject. Note that the UE 10may transmit the PCO including the fourth identification information.

The fourth identification information may be information representingthat the UE 10 does not support the operation mode allowed based on theoperator policy and/or information representing that the operation modeallowed based on the operator policy does not comply with the policy ofthe UE 10.

The PDN connectivity reject message ID may be a message typerepresenting the PDN connectivity reject message. The Cause may beinformation representing a reason why the PDN connectivity request isrejected. Here, the UE 10 may notify the UE 10 of the fourthidentification information included in the Cause. The Tw1 value may be avalue of the Tw1 timer, included when the Cause represents insufficientresources.

The TWAG 74 may receive the PDN connectivity reject transmitted from theUE 10. Based on the reception of the PDN connectivity reject and/or thefourth identification information included in the PDN connectivityreject, the TWAG 74 may delete the EPS bearer context, held by the TWAG74, relating to the established PDN connection. Furthermore, the TWAG 74may transmit, to the PGW 30, the fourth identification informationincluded in the PDN connectivity reject.

The PGW 30 may receive the fourth identification information transmittedfrom the TWAG 74. Based on the reception of the fourth identificationinformation and/or the operator policy, the PGW 30 may delete the EPSbearer context, held by the PGW 30, relating to the established PDNconnection.

Furthermore, the PGW 30 may perform the IP-CAN session update procedurewith the PCRF 60, based on the reception of the fourth identificationinformation. The PGW 30 may include the fourth identificationinformation in the IP-CAN session update procedure.

The PCRF 60 may change the operator policy based on the IP-CAN sessionupdate procedure. Note that based on the change of the operator policy,the PGW 30 may delete the EPS bearer context, held by the PGW 30,relating to the established PDN connection.

1.4.2. Description of State after PDN Connectivity EstablishmentProcedure

Performing the above-described first to seventh PDN connectivityprocedures leads to a first state and a second state, both of which willbe described later. Note that an initial state in the additional attachprocedure may be the first state or the second state. Note that theinitial state in the additional attach procedure may not be limited tothe first or second state.

1.4.3. Description of First State

The first state will be described with reference to FIG. 13. In thefirst state, the UE 10 has established the first PDN connection with thecore network 90. However, the UE 10 has not yet established the secondPDN connection. In greater detail, the UE 10 has established the firstPDN connection with the PGW_A 1310. However, the UE 10 has notestablished the second PDN connection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection has been established via theaccess network B. In addition, in the first state, the UE 10 may be in astate of not being connected to the core network 90 via the accessnetwork A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The first state has been described above; however, the first state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection has been established throughthe access network B and the PDN connection has not been establishedthrough the access network A, for example.

1.4.4. Description of Second State

The second state will be described with reference to FIG. 14. In thesecond state, the UE 10 has established the first PDN connection withthe core network 90. Furthermore, the UE 10 has established the secondPDN connection with the core network 90. In greater detail, the UE 10has established the first PDN connection with the PGW_A 1310.Furthermore, the UE 10 has established the second PDN connection withthe PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_B 1320. Here, the transferpath may be a bearer.

In addition, the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network A.Thus, the second PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and theeNodeB 45, a transfer path between the eNodeB 45 and the SGW 35, and atransfer path between the SGW 35 and the PGW_B 1320. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection has been established via theaccess network B. Furthermore, the UE 10 may be in a state in which thesingle-access PDN connection has been established via the access networkA.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The second state has been described above; however, the second state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection has been established throughthe access network B and the single-access PDN connection has beenestablished through the access network A, for example.

1.5. Additional Attach Procedure

Hereinafter, an additional attach procedure will be described. The factthat the Operation mode of the first PDN connection is theNetwork-initiated mode means that, in other words, the UE 10 cannotinitiate the switching of the flow and/or the update of the routing ruleof the PDN connection. On the other hand, the PDN connectivity procedureand/or the attach procedure is initiated by the UE 10.

As discussed above, the second state is a state in which the UE 10 hasestablished the first PDN connection through only the access network B.That is, a transfer path through the LTE access network is not includedin the first PDN connection. Note that the transfer path may be a bearerand/or a communication path.

Accordingly, when the first PDN connection of the second state is in theNetwork-initiated mode, the network and/or the PCRF 60 cannot include atransfer path through the access network A in the first PDN connection.

As such, the UE 10 may execute a procedure to establish a transfer paththrough the access network A, based on the state transition to thesecond state and the Operation mode being in the Network-initiated mode.

Further, also in the case where the Operation mode of the first PDNconnection in the first state and/or the second state is theUE-initiated mode, the UE 10 may perform the establishment procedure ofa transfer path through the access network A, based on the routing rulestored by the UE 10.

To be specific, in the case where the routing rule of the first PDNconnection indicates that the LTE access is prioritized, the UE 10 mayexecute a procedure to add, to the first PDN connection, a transfer paththrough the access network A.

To be more specific, in the case where the UE 10 stores a routing ruleassociating a specific flow with the LTE access for the first PDNconnection, the UE 10 may execute the procedure to add a transfer paththrough the access network A.

To rephrase, in the case where the routing rule of the first PDNconnection does not indicate that the LTE access is prioritized, the UE10 does not execute the procedure to add, to the first PDN connection, atransfer path through the access network A.

To be more specific, in the case where the UE 10 does not store arouting rule associating a specific flow with the LTE access for thefirst PDN connection, the UE 10 does not execute the procedure to add atransfer path through the access network A. Details of the procedurewill be described below.

1.5.1 Example of First Additional Attach Procedure

Next, an example of a first additional attach procedure will bedescribed with reference to FIG. 17. As illustrated in FIG. 17, theinitial state of the example of the present procedure is the first state(S2302). A procedure to transition to the first state may be similar tothe aforementioned procedure, and detailed description thereof isomitted herein.

It is sufficient for the first state to be a state in which the UE 10has established the first PDN connection with the PGW 30 and/or thenetwork through the access network A. Specifically, the first state is astate in which the UE 10 has established the first PDN connection,through the TWAG 74, with the PGW_A selected by using the APN 1. Thefirst PDN connection may be the multi-access PDN connection.

The UE 10 performs the attach procedure through the access network A(S2304) based on having transitioned to the first state and havingestablished the first PDN connection in the Network-initiated mode.

Alternatively, the UE 10 may perform the attach procedure through theaccess network A, based on having transitioned to the first state inwhich the first PDN connection has been established in the UE-initiatedmode and based on the routing rule.

To be specific, based on the fact that the routing rule prioritizes theLTE access, the UE 10 may perform the attach procedure through theaccess network A.

Specifically, the UE 10 may perform the attach procedure through theaccess network A in the case where the transition to the first state hasbeen made in which the first PDN connection in the UE-initiated mode hasbeen established and the routing rule of the first PDN connectionindicates that the LTE access is prioritized.

More specifically, the UE 10 may perform the attach procedure throughthe access network A in the case where the transition to the first statehas been made in which the first PDN connection in the UE-initiated modehas been established and the UE 10 stores the routing rule associating aspecific flow with the LTE access for the first PDN connection.

In other words, the UE 10 does not perform the attach procedure throughthe access network A in the case where the routing rule of the first PDNconnection does not indicate that the LTE access is prioritized, even ifthe transition to the first state has been made in which the first PDNconnection in the UE-initiated mode has been established.

More specifically, the UE 10 does not perform the attach procedurethrough the access network A, even if the transition to the first statehas been made in which the first PDN connection in the UE-initiated modehas been established, in the case where the UE 10 does not store therouting rule associating a specific flow with the LTE access for thefirst PDN connection.

Note that, however, the UE 10 may transmit an attach request includingat least an APN and/or PDN connection ID.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2,in order to establish a single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish a multi-access PDNconnection and/or an APN that is not allowed to perform communicationbased on the NBIFOM.

That is, the UE 10 may request the establishment of a single-access PDNconnection using the APN 2 different from the APN 1 acquired from thenetwork when the first PDN connection is established.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

The UE 10 performs, during the attach procedure, an authenticationprocedure and a security association procedure with the MME 40, thePGW_A, and the PGW_B.

Based on the completion of the attach procedure, the UE 10 may acquirethe APN from the network.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2,in order to establish a single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish the multi-access PDNconnection and/or an APN that is not allowed to perform communicationbased on the NBIFOM.

That is, the UE 10 may establish the single-access PDN connection usingthe APN 2 different from the APN 1 acquired from the network based onthe establishment of the first PDN connection.

In the manner discussed above, the UE 10 and the core network 90transition from the first state to the second state (S2306).

Next, the UE 10 performs the PDN connectivity procedure through theaccess network A (S2308), based on having transitioned to the secondstate and based on the first PDN connection having been established inthe Network-initiated mode.

Alternatively, the UE 10 may perform the PDN connectivity procedurethrough the access network A, based on having transitioned to the secondstate and based on the routing rule of the first PDN connection havingbeen established in the UE-initiated mode.

To be specific, based on the fact that the routing rule prioritizes theLTE access, the UE 10 may perform the attach procedure through theaccess network A.

Specifically, the UE 10 may execute a procedure to add a transfer path,through the access network A, in the first PDN connection in the casewhere the transition to the second state has been made in which thefirst PDN connection in the UE-initiated mode has been established andthe routing rule of the first PDN connection indicates that the LTEaccess is prioritized.

More specifically, the UE 10 may execute the procedure to add a transferpath through the access network A in the case where the transition tothe second state has been made in which the first PDN connection in theUE-initiated mode has been established and the UE 10 stores the routingrule associating a specific flow with the LTE access for the first PDNconnection.

In other words, the UE 10 does not execute the procedure to add atransfer path through the access network A in the first PDN connection,even if the transition to the second state has been made in which thefirst PDN connection in the UE-initiated mode has been established, inthe case where the routing rule of the first PDN connection does notindicate that the LTE access is prioritized.

More specifically, the UE 10 does not execute the procedure to add atransfer path through the access network A, even if the transition tothe second state has been made in which the first PDN connection in theUE-initiated mode has been established, in the case where the UE 10 doesnot store the routing rule associating a specific flow with the LTEaccess for the first PDN connection.

The PDN connectivity procedure through the access network A will bedescribed with reference to FIG. 18.

First, the UE 10 transmits a PDN connectivity request to the MME 40through the eNodeB 45 (S2402). The UE 10 may transmit the PDNconnectivity request including at least the PDN connectivity requestmessage ID (PDN connectivity request message identity), the proceduretransaction ID (Procedure transaction identity), the request type(Request type), the PDN type, the protocol discriminator (Protocoldiscriminator), and the EPS bearer ID (EPS bearer identity).Furthermore, the UE 10 may include at least the first identificationinformation and/or sixth identification information and/or the PDNconnection ID in the PDN connectivity request. Moreover, the UE 10 mayinclude the Access Point Name (APN) and/or Protocol ConfigurationOptions (PCOs) and/or the Traffic Flow Templates (TFTs) in the PDNconnectivity request. Note that the UE 10 may transmit the PCO includingthe first identification information and/or the sixth identificationinformation and/or the TFT and/or the PDN connection ID.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the possession ofthe function of establishing the multi-access PDN connection.

In addition, the sixth identification information may be a RequestNBIFOM representing that a request to determine the NBIFOM operationmode for the multi-access PDN connection. Additionally/alternatively,the sixth identification information may be information representingthat a request for an NBIFOM operation mode allowed for the multi-accessPDN connection to be established.

As described above, the UE 10 may transmit the PDN connectivity requestincluding the first identification information and/or sixthidentification information to request the establishment of themulti-access PDN connection, without requesting a specific NBIFOMoperation mode.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message. The proceduretransaction ID may be information for identifying the PDN connectivityprocedure.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1in order to establish the multi-access PDN connection. Here, the APN 1may be an APN that is allowed to establish the multi-access PDNconnection and/or an APN that is allowed to perform communication basedon the NBIFOM. Further, the APN may be identification information foridentifying the first PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30. Further, the PDN connection ID may beidentification information for identifying the first PDN connection. ThePDN connection ID may be associated with the APN.

Note that the UE 10 may identify the first PDN connection by using theAPN and/or the PDN connection ID.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The protocol discriminator may be a discriminator representing the typeof the protocol used when transmitting/receiving the PDN connectivityrequest.

The EPS bearer ID may be information for identifying the EPS bearer. TheEPS bearer ID may be assigned by the MME 40.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or the sixth identification information.

The TFT may be information for identifying an IP flow that performscommunication by using the PDN connection established in the present PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, by the TFT, user data of a specificapplication can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a specific NBIFOM operation mode,and thus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection without requesting thespecific NBIFOM operation mode, the UE 10 may transmit the PDNconnectivity request without including the TFT. More specifically, whenthe UE 10 includes the first identification information and/or the sixthidentification information, the UE 10 may transmit the PDN connectivityrequest without including the TFT.

Note that in the related art, the UE 10 can perform transmission, withinformation indicating the IFOM support included in the PCO. Here, theIFOM support is identification information representing that the IP FlowMobility (IFOM) is supported. Furthermore, the IFOM is a technique forswitching a communication path of a specific IP flow by using the DualStack Mobile IPv6 (DSMIPv6) protocol. Thus, including the informationindicating the IFOM support in the PCO allows the UE 10 to switch theaccess network through which the communication of a specific IP flow isperformed.

In the present embodiment, when the UE 10 includes the firstidentification information and the sixth identification information inthe PCO, the UE 10 does not include the IFOM support. In contrast, whenthe UE 10 includes the IFOM support in the PCO, the UE 10 does notinclude the first identification information and/or the sixthidentification information. As described above, it may be possible tonot configure both the first identification information and/or sixthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 can establish either the PDN connection supporting theIFOM or the PDN connection supporting the NBIFOM, in the establishmentprocedure of a single PDN connection. In other words, the single PDNconnection is any one of the PDN connection supporting the NBIFOM, thePDN connection supporting the IFOM, or the single-access PDN connection.

The MME 40 receives the PDN connectivity request transmitted from the UE10. Based on the reception of the PDN connectivity request, and/or thefirst identification information included in the PDN connectivityrequest as well as the sixth identification information included in thePDN connectivity request, the MME 40 transmits a Create Session Requestto the SGW 35 (S2404).

Based on the reception of the PDN connectivity request and/or the firstidentification information included in the PDN connectivity request, theMME 40 may transmit the Create Session Request including at least thefirst identification information.

Based on the reception of the PDN connectivity request and/or the sixthidentification information included in the PDN connectivity request, theMME 40 may transmit the Create Session Request including at least thesixth identification information. Furthermore, the MME 40 may includethe TFT in the Create Session Request, based on the reception of the TFTtransmitted from the UE 10.

Furthermore, the MME 40 may include the APN and/or the PDN connection IDin the Create Session Request, based on the reception of the APN and/orthe PDN connection ID transmitted from the UE 10. Note that the MME 40may identify the first PDN connection by using the APN and/or the PDNconnection ID having been received.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the PDN connectivityrequest, the MME 40 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the MME 40 may execute a procedure forestablishing the single-access PDN connection.

The SGW 35 receives the Create Session Request transmitted from the MME40. Based on the reception of a session connectivity request, and/or thefirst identification information and/or sixth identification informationincluded in the session connectivity request, the SGW 35 transmits theCreate Session Request to the PGW 30 (S2206).

Based on the reception of the session connectivity request, and/or thefirst identification information and/or sixth identification informationincluded in the session connectivity request, the SGW 35 may transmitthe Create Session Request including at least the first identificationinformation and/or sixth identification information. Further, the SGW 35may include the TFT in the Create Session Request.

Furthermore, the SGW 35 may include the APN and/or the PDN connection IDin the Create Session Request, based on the reception of the APN and/orthe PDN connection ID transmitted from the MME 40. Note that the SGW 35may identify the first PDN connection by using the APN and/or the PDNconnection ID having been received.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the Create SessionRequest, the SGW 35 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the MME 40 may execute a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the SGW35. Based on the reception of the Create Session Request, and/or thefirst identification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure with the PCRF 60 (S2408).

Based on the reception of the Create Session Request and/or the firstidentification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure including at least the firstidentification information and/or the sixth identification information.

Further, the PGW 30 may identify the first PDN connection by using theAPN and/or the PDN connection ID having been received, based on thereception of the APN and/or the PDN connection ID transmitted from theSGW 35.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or the eNodeB 45and/or the MME 40 and/or the SGW 35.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection or thesingle-access PDN connection, and/or the first identificationinformation, and/or the sixth identification information.

More specifically, when the multi-access PDN connection is to beestablished, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network A, the PDN connection ID, the informationindicating that the PDN connection is the multi-access PDN connection,and the first identification information and/or sixth identificationinformation. Alternatively, when the single-access PDN connection is tobe established, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network A, the PDN connection ID, and theinformation indicating that the PDN connection is the single-access PDNconnection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, based on the reception of the first identificationinformation and/or sixth identification information, the PCRF 60 maytransmit, to the PGW 30, a control message in the IP-CAN session updateprocedure with the PGW 30, the control message including at least theseventh identification information. The detailed description of theseventh identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 transmits aCreate Session Response to the SGW 35 (S2410).

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 may transmitthe Create Session Response including at least the seventhidentification information.

Furthermore, the PGW 30 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in the Create Session Response.

Note that a method by which the PGW 30 acquires the seventhidentification information is not limited to the above-described methodfor acquiring the seventh identification information from the PCRF 60 inthe IP-CAN session update procedure, and another example may beemployed. For example, the PGW 30 may create the seventh identificationinformation and transmit the Create Session Response including theseventh identification information, without acquiring the seventhidentification information from the PCRF 60 in the IP-CAN session updateprocedure.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection to be established. In other words, theseventh identification information may be an operation mode allowed bythe operator.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode orthe seventh identification information based on the operator policy. Forexample, a policy that allows for the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows for theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows for the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

Based on the Allowed Mode, the PCRF 60 or the PGW 30 may include theallowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both of the UE-Initiated mode and the Network-Initiatedmode are allowed, the seventh identification information may includeboth the operation modes. Alternatively, when both of the UE-Initiatedmode and the Network-Initiated mode are allowed and a default operationmode is configured, the seventh identification information may includeonly the default operation mode. Note that which of the UE-Initiatedmode and the Network-Initiated mode is defined as the default operationmode may be configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the Requested Operation Mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the MME 40 of the seventhidentification information through the SGW 35.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may transmit, to the MME 40 through the SGW 35,the Create Session Response including the cause information indicatingthat the Requested Operation Mode is not allowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the MME 40 through the SGW 35 thatthere is no allowed operation.

As described above, based on the Allowed Mode, the PCRF 60 or the PGW 30may regard an operation mode that is allowed for establishment of thePDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theMME 40 through the SGW 35. Thus, in this case, the PGW 30 need notinclude either the TFT or the PDN address in the Create SessionResponse.

In other words, only when the Network-Initiated mode is included in theseventh identification information, the PGW 30 may transmit the TFT tothe MME 40 through the SGW 35. Thus, in this case, the PGW 30 mayinclude the TFT and the PDN address (PDN Address) in the Create SessionResponse.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the MME 40. In other words, the PGW 30 may assign the PDNconnection ID.

The SGW 35 receives the Create Session Response transmitted from the PGW30. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the SGW 35 transmits the Create Session Response to the MME 40(S2412).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theSGW 35 may transmit the Create Session Response including at least theseventh identification information.

Furthermore, the SGW 35 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in a session request response.

The MME 40 receives the Create Session Response transmitted from the SGW35. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the MME 40 transmits an activated default EPS bearer contextrequest (Activated default EPS bearer context request) to the eNodeB 45(S2414).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theMME 40 may transmit the activated default EPS bearer context requestincluding at least an activated default EPS bearer context requestmessage ID (Activated default EPS bearer context request messageidentity), the procedure transaction ID, the APN, the PDN address (PDNAddress), the protocol discriminator, the EPS bearer ID, and the EPSQoS. Further, the MME 40 may include at least the seventh identificationinformation in the activated default EPS bearer context request.Furthermore, the MME 40 may include the PCO and/or the ESM Cause and/orthe TFT and/or the PDN connection ID and/or the PDN connection attributeinformation in the activated default EPS bearer context request. Notethat the MME 40 may transmit the PCO including the seventhidentification information and/or the TFT and/or the PDN connection ID.

Here, the activated default EPS bearer context request message ID may bea message type representing the activated default EPS bearer contextrequest message.

The APN may be an APN to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection. The MME 40 mayinclude the APN 1 in the activated default EPS bearer context request.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The EPS QoS may be a state representing the EPS bearer QoS.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted/received by using the PDNconnection established in the PDN connectivity procedure is allowed tobe transmitted/received through the access network A and the accessnetwork B, and/or information indicating that the PDN connectionestablished in the present PDN connectivity procedure is themulti-access PDN connection of the operation mode indicated by theseventh identification information.

Note that the UE 10 may transmit the activated default EPS bearercontext request message further including the connectivity type thatindicates the type of the PDN connection and/or the WLAN offloadpermission information (WLAN offload acceptability) indicating whetheror not the WLAN offload can be performed. Furthermore, the MME 40 maytransmit the connectivity type or the WLAN offload permissioninformation including the PDN connection attribute information.

The ESM Cause may be information representing that the PDN type of thePDN address assigned to the UE 10 is different from the PDN typerequested by the UE 10 in the PDN connectivity request.

Note that the MME 40 and/or the PGW 30 may include the seventhidentification information in the PCO. However, when the MME 40 and/orthe PGW 30 includes the seventh identification information in the PCO,the MME 40 and/or the PGW 30 does not include the IFOM support. Incontrast, when the MME 40 and/or the PGW 30 includes the IFOM support inthe PCO, the MME 40 and/or the PGW 30 does not include the seventhidentification information. As described above, it may be possible tonot configure both the seventh identification information and the IFOMsupport to be effective to ensure a clear distinction between the use ofthe switching of the communication path based on the NBIFOM and the useof the switching of the communication path based on the IFOM.

The eNodeB 45 receives the activated default EPS bearer context requesttransmitted from the MME 40. The eNodeB 45 transfers the activateddefault EPS bearer context request to the UE 10, based on the receptionof the activated default EPS bearer context request.

The eNodeB 45 may transmit at least an RRC connection reconfiguration(RRC Connection Reconfiguration) request to the UE 10 along with theactivated default EPS bearer context request (S2416).

The UE 10 receives the RRC connection reconfiguration requesttransmitted from the eNodeB 45. Further, the UE 10 receives theactivated default EPS bearer context request transmitted by the MME 40and then transferred by the eNodeB 45.

Based on the reception of the RRC connection reconfiguration request,the UE 10 transmits an RRC connection reconfiguration complete (RCCConnection Reconfiguration Complete) to the eNodeB 45 (S2418).

The eNodeB 45 receives the RRC connection reconfiguration completetransmitted from the UE 10. The eNodeB 45 transmits a bearerconfiguration to the MME 40 based on the RRC connection reconfigurationcomplete.

The MME 40 receives the bearer configuration transmitted from the eNodeB45 (S2420).

Based on the reception of the activated default EPS bearer contextrequest and/or the seventh identification information included in theactivated default EPS bearer context request, the UE 10 transmits, tothe MME 40, an Activate default EPS bearer context acceptor an Activatedefault EPS bearer context reject (S2422) (S2424).

The UE 10 may transmit the activated default EPS bearer context acceptincluding at least an Activate default EPS bearer context accept messageID (Activate default EPS bearer context accept message identity), theprocedure transaction ID, the protocol discriminator, and the EPS bearerID.

Further, the UE 10 may transmit the Activate default EPS bearer contextreject including at least an Activate default EPS bearer context rejectmessage ID (Activate default EPS bearer context reject messageidentity), the procedure transaction ID, the protocol discriminator, theEPS bearer ID, and the ESM Cause.

Furthermore, the UE 10 may include the PCO in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the Activate default EPS bearercontext accept or the Activate default EPS bearer context reject. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in theactivated default EPS bearer context request, the UE 10 may include theUE-Initiated mode or the Network-Initiated mode in the fifthidentification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

Here, the Activate default EPS bearer context accept message ID may be amessage type representing the Activate default EPS bearer context acceptmessage.

The Activate default EPS bearer context reject message ID may be amessage type representing the Activate default EPS bearer context rejectmessage.

The ESM Cause may be information representing the reason why theactivated default EPS bearer context request is rejected. With this, theUE 10 completes the supplemental attach procedure.

In other words, based on having transitioned to the first state andbased on the Operation mode of the first PDN connection, the UE 10 canestablish a supplemental transfer path through the LTE access network A.

To be specific, based on having transitioned to the first state and thefact that the first PDN connection is in the Network-initiated mode, theUE 10 performs the attach procedure and the PDN connectivity procedureon the LTE access network A so as to make it possible to establish thesupplemental transfer path through the eNB 45. Note that the transferpath may be a bearer and/or a communication path.

To be more specific, the UE 10 performs the attach procedure toestablish the second PDN connection between the UE 10 and the PGW_Bselected by using the APN 2, and thereafter performs the PDNconnectivity procedure so as to make it possible to add a transfer pathin the first PDN connection between the UE 10 and the PGW_A selected byusing the APN 1 through the LTE access network. Note that the transferpath may be a bearer and/or a communication path.

Alternatively, the UE 10 performs the attach procedure and the PDNconnectivity procedure on the LTE access network A, based on havingtransitioned to the first state and based on the routing rule of thefirst PDN connection in the UE-initiated mode, and makes it possible toestablish a supplemental transfer path through the eNB 45. Note that thetransfer path may be a bearer and/or a communication path.

To be specific, the UE 10 performs the attach procedure to establish thesecond PDN connection between the UE 10 and the PGW_B selected by usingthe APN 2, and thereafter performs the PDN connectivity procedure so asto make it possible to add the transfer path in the first PDN connectionbetween the UE 10 and the PGW_A selected by using the APN 1 through theLTE access network. Note that the transfer path may be a bearer and/or acommunication path.

Moreover, based on having transitioned to the second state and based onthe Operation mode of the first PDN connection, the UE 10 can establisha supplemental transfer path through the LTE access network A.

To be specific, based on having transitioned to the second state and thefact that the first PDN connection is in the Network-initiated mode, theUE 10 performs the PDN connectivity procedure on the LTE access networkA, thereby making it possible to establish the supplemental transferpath through the eNB 45. Note that the transfer path may be a bearerand/or a communication path.

To be more specific, the UE 10 performs the PDN connectivity procedureso as to make it possible to add a transfer path in the first PDNconnection between the UE 10 and the PGW_A selected by using the APN 1through the LTE access network. Note that the transfer path may be abearer and/or a communication path.

Alternatively, the UE 10 performs the PDN connectivity procedure on theLTE access network A, based on having transitioned to the second stateand based on the routing rule of the first PDN connection in theUE-initiated mode, so as to make it possible to establish a supplementaltransfer path through the eNB 45. Note that the transfer path may be abearer and/or a communication path.

To be specific, the UE 10 performs the PDN connectivity procedure so asto make it possible to add a transfer path in the first PDN connectionbetween the UE 10 and the PGW_A selected by using the APN 1 through theLTE access network. Note that the transfer path may be a bearer and/or acommunication path.

2. Second Embodiment

Hereinafter, a radio communication technology according to an embodimentof the present invention will be described in detail with reference tothe drawings.

2.1. System Overview

The mobile communication system in the present embodiment may be similarto that in the first embodiment. Thus, the overview of the mobilecommunication system is similar to that of the mobile communicationsystem described with reference to FIG. 1 in Chapter 2.1 of the firstembodiment, and therefore detailed description will be omitted.

In the present embodiment, the UE 10 can establish a first PDNconnection and/or a second PDN connection.

Furthermore, in the present embodiment, an NBIFOM is a technology thatallows establishment of a multi-access PDN connection.

Furthermore, in the present embodiment, the multi-access PDN connectionrefers to a PDN connection capable of accommodating, in one PDNconnection, a transfer path and/or a bearer over 3GPP access and/or WLANaccess. In other words, the multi-access PDN connection can combine andaccommodate a transfer path through the 3GPP access and a transfer paththrough the WLAN access. Note that the multi-access PDN connection maybe a PDN connection accommodating only a bearer through the 3GPP accessor may be a PDN connection accommodating only a transfer path throughthe WLAN access. In other words, the multi-access PDN connection is aPDN connection capable of constituting one or multiple transfer paths.

Note that in the present embodiment, unlike the first embodiment, themulti-access PDN connection may be a PDN connection established based onthe NBIFOM or a PDN connection established based on the IP Flow Mobility(IFOM). Thus, in the present embodiment, the multi-access PDN connectionmay be either the multi-access PDN connection corresponding to the PDNconnection in which a transfer path of a specific flow can be selectedbased on the NBIFOM or the multi-access PDN connection corresponding tothe PDN connection in which a transfer path of a specific flow can beselected based on the IFOM.

Note that the IFOM is a technology for switching a communication path ofa specific IP flow by using the Dual Stack Mobile IPv6 (DSMIPv6)protocol. On the other hand, the NBIFOM is a technology for switching acommunication path of a specific IP flow by using a network-basedmobility management protocol such as a General Packet Radio SystemTunneling Protocol (GTP) and a Proxy Mobile IP (PMIP). Furthermore, thefirst PDN connection may be the above-described multi-access PDNconnection.

In detail, the first PDN connection is a PDN connection in which, as onePDN connection, a communication path EPS bearer through the accessnetwork A and a communication path constituted by a GTP/PMIPv6 tunnelthrough the access network B can be used. That is, this PDN connectioncan transmit/receive data through the 3GPP access, the WLAN access, orboth thereof. The first PDN connection may be the multi-access PDNconnection.

Furthermore, the second PDN connection may be the PDN connection of therelated art, rather than the multi-access PDN connection. Note that thesecond PDN connection may be a single-access PDN connection.

Here, the single-access PDN connection refers to one PDN connectionconstituted of only a transfer path of either the 3GPP access or theWLAN access, unlike the multi-access PDN connection. In detail, thesingle-access PDN connection is a PDN connection established by theattach of the related art.

That is, the second PDN connection is a PDN connection constituted ofthe EPS bearer through the access network A or a PDN connectionconstituted of the GTP/PMIPv6 transfer path through the access networkB. The second PDN connection accommodates a transfer path and/or acommunication path through either one of the access networks.

As described above, the single-access PDN connection is a PDN connectiondifferent from the multi-access PDN connection. Moreover, thesingle-access PDN connection is a PDN connection that is also differentfrom a PDN connection for a Local IP Access (LIPA). Here, the LIPArefers to communication control for performing offload to a homenetwork. More specifically, the base station to which the terminaldevice connects performs the offload by transmitting, to the homenetwork to which the base station connects, user data delivered via thecore network 90 in the related art. The PDN connection for the LIPA is aPDN connection for performing such communication based on the LIPA.

Next, an example of a configuration of the core network 90 will bedescribed. FIG. 2A illustrates an example of a configuration of the IPmobile communication network. As illustrated in FIG. 2A, the corenetwork 90 is constituted of the Home Subscriber Server (HSS) 50, theAuthentication, Authorization, Accounting (AAA) 55, the Policy andCharging Rules Function (PCRF) 60, the PGW 30, the enhanced Packet DataGateway (ePDG) 65, the SGW 35, the MME 40, and the Serving GPRS SupportNode (SGSN) 45.

Furthermore, the core network 90 can be connected to multiple radioaccess networks (the LTE AN 80, the WLAN ANb 75, the WLAN ANa 70, theUTRAN 20, and the GERAN 25).

A radio access network may be constituted of multiple different accessnetworks, or may be constituted of either one of the access networks.Moreover, the UE 10 can be wirelessly connected to the radio accessnetwork.

Moreover, the WLAN access network b (WLAN ANb 75) that connects to thecore network 90 via the ePDG 65 and the WLAN access network a (WLAN ANa75) that connects to the PGW 30, the PCRF 60, and the AAA 55 can beconfigured as the access network connectable in the WLAN access system.

Note that each device has a similar configuration to those of thedevices of the related art in a mobile communication system using EPS,and thus detailed descriptions thereof will be omitted. Each device willbe described briefly hereinafter.

The PGW 30 is connected to the PDN 100, the SGW 35, the ePDG 65, theWLAN ANa 70, the PCRF 60, and the AAA 55 and is a relay deviceconfigured to transfer user data by functioning as a gateway devicebetween the PDN 100 and the core network 90.

The SGW 35 is connected to the PGW 30, the MME 40, the LTE AN 80, theSGSN 45, and the UTRAN 20 and is a relay device configured to transferuser data by functioning as a gateway device between the core network 90and the 3GPP access network (the UTRAN 20, the GERAN 25, and the LTE AN80).

The MME 40 is connected to the SGW 35, the LTE AN 80, and the HSS 50 andis an access control device configured to perform location informationmanagement and access control for the UE 10 via the LTE AN 80.Furthermore, the core network 90 may include multiple locationmanagement devices. For example, a location management device differentfrom the MME 40 may be constituted. The location management devicedifferent from the MME 40 may be connected to the SGW 35, the LTE AN 80,and the HSS 50, as with the MME 40.

Furthermore, when multiple MMEs 40 are included in the core network 90,the MMEs 40 may be connected to each other. With this configuration, thecontext of the UE 10 may be transmitted/received among the MMEs 40.

The HSS 50 is connected to the MME 40 and the AAA 55 and is a managingnode configured to manage subscriber information. The subscriberinformation of the HSS 50 is referenced during access control for theMME 40, for example. Moreover, the HSS 50 may be connected to thelocation management device different from the MME 40.

The AAA 55 is connected to the PGW 30, the HSS 50, the PCRF 60, and theWLAN ANa 70 and is configured to perform access control for the UE 10connected via the WLAN ANa 70.

The PCRF 60 is connected to the PGW 30, the WLAN ANa 75, the AAA 55, andthe PDN 100 and is configured to perform QoS management on datadelivery. For example, the PCRF 60 manages QoS of a communication pathbetween the UE 10 and the PDN 100.

The ePDG 65 is connected to the PGW 30 and the WLAN ANb 75 and isconfigured to deliver user data by functioning as a gateway devicebetween the core network 90 and the WLAN ANb 75.

The SGSN 45 is connected to the UTRAN 20, the GERAN 25, and the SGW 35and is a control device for location management between a 3G/2G accessnetwork (UTRAN/GERAN) and the LTE access network (E-UTRAN). In addition,the SGSN 45 has functions of: selecting the PGW 30 and the SGW 35;managing a time zone of the UE 10; and selecting the MME 40 at the timeof handover to the E-UTRAN.

Also, as illustrated in FIG. 2B, each radio access network includesdevices to which the UE 10 is actually connected (for example, a basestation device and an access point device), and the like. The devicesused in these connections are assumed to adapt to the radio accessnetworks.

In the present embodiment, the LTE AN 80 includes the eNB 45. The eNB 45is a radio base station to which the UE 10 connects in an LTE accesssystem, and the LTE AN 80 may include one or multiple radio basestations.

The WLAN ANa 70 includes the WLAN APa 72 and the TWAG 74. The WLAN APa72 is a radio base station to which the UE 10 connects in the WLANaccess system trusted by the operator running the core network 90, andthe WLAN ANa 70 may include one or multiple radio base stations. The GW74 is a gateway device between the core network 90 and the WLAN ANa 70.Furthermore, the WLAN APa 72 and the GW 74 may be constituted as asingle device.

Even in a case where the operator running the core network 90 and theoperator running the WLAN ANa 70 are different, such a constitution canbe implemented through contracts and agreements between the operators.

Furthermore, the WLAN ANb 75 includes the WLAN APb 76. The WLAN APb 76is a radio base station to which the UE 10 connects in the WLAN accesssystem in a case where no trusting relationship is established with theoperator running the core network 90, and the WLAN ANb 75 may includeone or multiple radio base stations.

In this manner, the WLAN ANb 75 is connected to the core network 90 viathe ePDG 65, which is a device included in the core network 90, servingas a gateway. The ePDG 65 has a security function for ensuring thesecurity of communication.

The UTRAN 20 includes the Radio Network Controller (RNC) 24 and the eNB(UTRAN) 22. The eNB (UTRAN) 22 is a radio base station to which the UE10 connects through a UMTS Terrestrial Radio Access (UTRA), and theUTRAN 20 may include one or multiple radio base stations. Furthermore,the RNC 24 is a control unit configured to connect the core network 90and the eNB (UTRAN) 22, and the UTRAN 20 may include one or multipleRNCs. Moreover, the RNC 24 may be connected to one or multiple eNBs(UTRANs) 22. In addition, the RNC 24 may be connected to a radio basestation (Base Station Subsystem (BSS) 26) included in the GERAN 25.

The GERAN 25 includes the BSS 26. The BSS 26 is a radio base station towhich the UE 10 connects through GSM/EDGE Radio Access (GERA), and theGERAN 25 may be constituted of one or multiple radio base station BSSs.Furthermore, the multiple BSSs may be connected to each other. Moreover,the BSS 26 may be connected to the RNC 24.

Note that in the present specification, the UE 10 being connected toradio access networks refers to the UE 10 being connected to a basestation device, an access point, or the like included in each radioaccess network, and data, signals, and the like beingtransmitted/received also pass through those base station devices,access points, or the like.

2.2 Device Configuration

The configuration of each device will be described below.

2.2.1. TWAG Configuration

FIG. 3 illustrates a device configuration of the TWAG 74. As illustratedin FIG. 3, the TWAG 74 is constituted of an IP mobile communicationnetwork interface unit 320, a control unit 300, and a storage 340. TheIP mobile communication network interface unit 320 and the storage 340are connected to the control unit 300 via a bus.

The control unit 300 is a function unit for controlling the TWAG 74. Thecontrol unit 300 implements various processes by reading out andexecuting various programs stored in the storage 340.

The IP mobile communication network interface unit 320 is a functionunit through which the TWAG 74 is connected to the PGW 30.

The storage 340 is a function unit for storing programs, data, and thelike necessary for each operation of the TWAG 74. The storage 340 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 3, the storage 340 stores a TWAG capability 342,a Network capability 344, and an EPS bearer context 346. Hereinafter,information elements stored in the storage 340 will be described.

FIGS. 4A to 4E illustrate the information elements stored in the storage340. FIG. 4A illustrates an example of the TWAG capability stored by theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether or not capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether or not the TWAG 74 supports an NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in the drawing, the NBIFOM capability may be stored whilebeing associated with the TWAG ID that is the identification informationon the TWAG 74. If not associated with the TWAG ID, the NBIFOMcapability may mean capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored while beingassociated with each other, the TWAG 74 may store the TWAG capability ofmultiple TWAGs 74.

In this case, when the UE 10 performs a handover to another TWAG 74, theTWAG 74 may select a TWAG 74 to which the handover is made, based on theTWAG capability.

Next, the Network capability 344 will be described. FIG. 4B illustratesan example of the Network capability stored by the TWAG 74. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. In other words, the identificationinformation indicates whether or not the PGW 30 supports the NBIFOMfunction. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

As illustrated in FIG. 4B, the TWAG 74 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 4B, theNBIFOM capability may be stored associated with each of the multiplePGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean Access Point Name (APN), for example.

Next, the EPS bearer context will be described. The EPS bearer contextmay be classified into an EPS bearer context for each UE 10 stored foreach UE 10, an EPS bearer context for each PDN connection, and an EPSbearer context for each bearer and/or transfer path.

FIG. 4C illustrates information elements included in the EPS bearercontext for each UE 10. As is obvious from FIG. 4C, the TWAG 74 stores,for each UE 10, a UE NBIFOM capability and an NBIFOM allowed.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information indicating whether or not the UE 10 supportsthe NBIFOM function. More specifically, for example, the UE NBIFOMcapability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection based on the NBIFOM based on the NBIFOM. In other words, inthe present embodiment, the UE 10 is allowed to establish themulti-access PDN connection based on the NBIFOM by using the APN 1. Notethat the APN 1 is also allowed to establish the PDN connection of therelated art, rather than the multi-access PDN connection based on theNBIFOM.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection based on theNBIFOM. That is, in the present embodiment, the UE 10 cannot establishthe multi-access PDN connection based on the NBIFOM by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished. The TWAG 74 may access the HSS 50 to acquire the NBIFOMallowed before the PDN connection is established and/or during theestablishment procedure.

Furthermore, the EPS bearer context for each UE 10 may includeidentification information on the UE 10. The identification informationon the UE 10 may be an IMSI.

Furthermore, FIG. 4D illustrates the EPS bearer context for each PDNconnection. The EPS bearer context for each PDN connection includes aPDN connection ID, a Network allowed mode, an Operation mode, a Userplane connection ID, a TWAG MAC address, and an NBIFOM Permission.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the PDN connection is the first PDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be a UE initiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The User plane connection ID is identification information foridentifying a connection used for transmission of user data when the UE10 establishes a transfer path via the TWAG 74.

The TWAG MAC address is a physical address of the TWAG 74.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection based on the NBIFOM. Inother words, the NBIFOM permission indicates that the first PDNconnection has been established.

That is, the fact that the TWAG 74 has stored the NBIFOM permissionmeans that this PDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored bythe TWAG 74 upon the PDN connection being established.

The TWAG 74 may access the HSS 50 to acquire the NBIFOM permissionduring the establishment of the PDN connection. Alternatively, the TWAG74 may store the NBIFOM Permission based on the establishment of themulti-access PDN connection based on the NBIFOM.

Next, the EPS bearer context for each bearer and/or transfer path willbe described. As illustrated in FIG. 4E, the EPS bearer context for eachbearer and/or transfer path may include the transfer path identificationinformation and the Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Based on this association,whether using a communication path through the 3GPP access network orusing a communication path through the WLAN access network isdetermined.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60, or maybe notified from the UE 10. Alternatively, the Routing Rule may be avalue that the TWAG 74 prestores as a default value.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the flow can be switched for each application. Alternatively,the Routing Filter may include the TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule.

The TWAG capability and the Network capability may be included in theEPS bearer context.

2.2.2. HSS Configuration

Next, the configuration of the HSS 50 will be described. FIG. 5illustrates a device configuration of the HSS 50. As illustrated in FIG.5, the HSS 50 is constituted of an IP mobile communication networkinterface unit 520, a control unit 500, and a storage 540. The IP mobilecommunication network interface unit 520 and the storage 540 areconnected to the control unit 500 via a bus.

The control unit 500 is a function unit for controlling the HSS 50. Thecontrol unit 500 implements various processes by reading out andexecuting various programs stored in the storage 540.

The IP mobile communication network interface unit 520 is a functionunit through which the HSS 50 is connected to the MME 40 and/or anotherMME 40, and the AAA 55.

The storage 540 is a function unit for storing programs, data, and thelike necessary for each operation of the HSS 50. The storage 540 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 5, the storage 540 stores HSS data 542.Hereinafter, information elements stored in the storage 540 will bedescribed.

FIGS. 6A and 6B illustrate the information elements stored in thestorage 540. FIG. 6A illustrates an example of HSS data for each UE 10stored by the HSS 50.

As is obvious from FIG. 6A, the HSS data for each UE 10 includes anIMSI, an MSISDN, an IMEI/IMEISV, an Access Restriction, a UE NBIFOMcapability, and an NBIFOM allowed.

The IMSI is identification information assigned to a user (subscriber)using the UE 10. The MSISDN represents the phone number of the UE 10.The IMEI/IMISV is identification information assigned to the UE 10. TheAccess Restriction indicates registration information for accessrestriction.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capabilityindicates whether or not the UE 10 supports the NBIFOM function. Morespecifically, for example, the NBIFOM capability may include “allowed”or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection based on the NBIFOM. In other words, in the presentembodiment, the UE 10 is allowed to establish the multi-access PDNconnection based on the NBIFOM by using the APN 1. Note that the APN 1is also allowed to establish the PDN connection of the related art,rather than the multi-access PDN connection based on the NBIFOM.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection based on theNBIFOM. That is, in the present embodiment, the UE 10 cannot establishthe multi-access PDN connection based on the NBIFOM by using the APN 2.The NBIFOM allowed may be stored before the PDN connection isestablished.

FIG. 6B illustrates an example of HSS data for each PDN connectionstored by the HSS 50. As is obvious from FIG. 6B, the HSS data for eachPDN connection includes at least a Context ID, a PDN address, a PDNType, an Access Point Name (APN), a WLAN offload ability, a PDN GW ID,and an NBIFOM Permission.

The Context ID is identification information on the context storing theHSS data for each PDN connection. The PDN Address represents aregistered IP address. The PDN Address is an IP address of the UE 10.The PDN Type indicates the type of PDN Address. That is, the PDN Type isidentification information for identifying IPv4, IPv6, or IPv4v6, forexample. The APN is a label indicating an access destination in thenetwork, in accordance with DNS naming convention.

The WLAN offload ability is identification information indicatingwhether traffic connected through this APN can perform offload to theWLAN by utilizing a cooperative function between the WLAN and the 3GPP,or maintains the 3GPP connection. The WLAN offload ability may vary foreach RAT type. Specifically, the LTE (E-UTRA) and the 3G (UTRA) may havedifferent WLAN offload ability.

The PDN GW identity is identification information for identifying thePGW 30 utilized in this APN. This identification information may be aFully Qualified Domain Name (FQDN) or an IP address.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection based on the NBIFOM. Inother words, the NBIFOM permission indicates that the first PDNconnection has been established.

That is, the fact that the TWAG 74 has stored the NBIFOM permissionmeans that this PDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored bythe TWAG 74 upon the PDN connection being established.

Specifically, for example, the HSS data for each PDN connectionincluding the APN 1 may include the NBIFOM Permission, and the HSS datafor each PDN connection including the APN 2 need not include the NBIFOMPermission.

In other words, the PDN connection based on the APN 1 may be the firstPDN connection, and the PDN connection based on the APN 2 cannot be thefirst PDN connection.

2.2.3. UE Configuration

Next, the configuration of the UE 10 will be described. FIG. 7illustrates a device configuration of the UE 10. As illustrated in FIG.7, the UE 10 is constituted of an LTE interface unit 720, a WLANinterface unit 740, a control unit 700, and a storage 750.

The LTE interface unit 720, the WLAN interface unit 740, and the storage750 are connected to the control unit 700 via a bus.

The control unit 700 is a function unit for controlling the UE 10. Thecontrol unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The LTE interface unit 720 is a function unit through which the UE 10connects to an IP access network via an LTE base station. Furthermore,an external antenna 710 is connected to the LTE interface unit 720.

The WLAN interface unit 740 is a function unit through which the UE 10connects to the IP access network via a WLAN AP. Furthermore, anexternal antenna 730 is connected to the WLAN interface unit 740.

The control unit 700 is a function unit for controlling the UE 10. Thecontrol unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The storage 750 is a function unit for storing programs, data, and thelike necessary for each operation of the UE 10. The storage 750 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 7, the storage 750 stores a UE context 752.Hereinafter, information elements stored in the storage 750 will bedescribed. Note that the UE context 752 is classified into a UE contextfor each UE 10, a UE context for each PDN connection, and a UE contextfor each transfer path and/or bearer.

FIG. 8A is an example of the UE context stored for each UE 10. Asillustrated in FIG. 8A, the UE context for each UE 10 includes an IMSI,an EMM State, a GUTI, an ME Identity, and a UE NBIFOM capability.

The IMSI is identification information assigned to a user (subscriber)using the UE 10. The EMM State indicates a mobility management state ofthe UE 10. For example, the EMM State may be EMM-REGISTERED in which theUE 10 is registered with the network (registered state) orEMM-DEREGISTERD in which the UE 10 is not registered with the network(deregistered state).

The GUTI is an abbreviation of “Globally Unique Temporary Identity,” andis temporary identification information on the UE 10. The GUTI isconstituted of identification information on the MME 40 (Globally UniqueMME Identifier (GUMMEI)) and identification information on the UE 10 ina specific MME 40 (M-TMSI). The ME identity is an ID of an ME, and maybe the IMEI/IMISV, for example.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information for each UE 10 indicating whether or not theNBIFOM function is supported. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability in the storage of the UE 10 may mean that the UE 10 has thefunction of establishing the first PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage of the UE10 may mean that the UE 10 supports the NBIFOM function.

FIG. 8B illustrates an example of the UE context for each PDNconnection. As illustrated in FIG. 8B, the UE context for each PDNconnection includes at least a PDN connection ID, an APN in Use, an IPaddress, a Default Bearer, a WLAN offload ability, a UE allowed mode,and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The APN in Use is an APN utilized by the UE 10 most recently. This APNmay be constituted of identification information on the network andidentification information on a default operator.

The IP Address is an IP address assigned to the UE 10 through the PDNconnection, and may be an IPv4 address or an IPv6 prefix.

The Default Bearer is EPS bearer identification information foridentifying a default bearer in this PDN connection.

The WLAN offloadability is WLAN offload permission informationindicating whether or not a communication associated with this PDNconnection allows for offload to the WLAN using an interworking functionbetween the WLAN and the 3GPP, or maintains the 3GPP access.

The UE allowed mode is an Operation mode allowed by the UE 10. Thisidentification information may indicate the UE initiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the current PDN connection is the first PDN connection.

FIG. 8C illustrates the UE context for each bearer. The UE context foreach bearer includes transfer path identification information and aRouting Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the UE 10 can switch the flow for each application.Alternatively, the Routing Filter may include a TFT.

The Routing Rule may store multiple rules (regulations). Furthermore,the Routing Rule may include priority for each rule.

FIG. 8D illustrates the TWAG capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether or not capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether or not the TWAG 74 supportsan NBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The UE 10 may store the NBIFOM capability associated with the TWAG ID.Furthermore, the NBIFOM capability of multiple TWAGs 74 may be stored.

FIG. 8E illustrates an example of the Network capability. In the Networkcapability, the NBIFOM capability is stored for each network, i.e., foreach PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 8E, the TWAG 74 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 4B, theNBIFOM capability may be stored associated with each of the multiplePGWs 30.

The PGW ID is information for identifying the PGW 30. The PGW ID may bean APN, for example.

The TWAG capability and the Network capability may be included in the UEcontext, or may be information separated from the UE context.

That is, the UE 10 may store the TWAG capability and the Networkcapability included in the UE context, or may store the TWAG capabilityand the Network capability separately from the UE context.

2.2.4. PGW Components

Next, the components of the PGW 30 will be described. FIG. 9 illustratesa device configuration of the PGW 30. As illustrated in FIG. 9, the PGW30 is constituted of an IP mobile communication network interface unit920, a control unit 900, and a storage 940. The IP mobile communicationnetwork interface unit 920 and the storage 940 are connected to thecontrol unit 900 via a bus.

The control unit 900 is a function unit for controlling the PGW 30. Thecontrol unit 900 implements various processes by reading out andexecuting various programs stored in the storage 940.

The IP mobile communication network interface unit 920 is a functionunit through which the PGW 30 is connected to the SGW 35 and/or the PCRF60 and/or the ePDG 65 and/or the AAA 55 and/or the GW 74.

The storage 940 is a function unit for storing programs, data, and thelike necessary for each operation of the PGW 30. The storage 940 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 9, the storage 940 stores an EPS bearer context942. Note that the EPS bearer context includes an EPS bearer contextstored for each UE 10, an EPS bearer context stored for each APN, an EPSbearer context stored for each PDN connection, and an EPS bearer contextstored for each transfer path and/or bearer.

First, the EPS bearer context for each UE 10 will be described. FIG. 10Aillustrates an example of the EPS bearer context for each UE 10. Asillustrated in FIG. 10A, the EPS bearer context includes at least anIMSI, an ME identity, an MSISDN, and a UE NBIFOM capability.

The IMSI is information for identifying a user of the UE 10. The MEidentity is an ID of an ME, and may be the IMEI/IMISV, for example. TheMSISDN represents the phone number of the UE 10.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

Next, the EPS bearer context for each PDN connection will be described.FIG. 10B illustrates an example of the EPS bearer context for each PDNconnection.

As illustrated in FIG. 10B, the context includes at least a PDNconnection ID, an IP address, a PDN type, an APN, a Network allowedmode, and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The IP Address indicates an IP address assigned to the UE 10 for thisPDN connection. The IP address may be an IPv4 and/or IPv6 prefix.

The PDN type indicates the type of the IP address. The PDN typeindicates IPv4, IPv6 or IPv4v6, for example.

The APN is a label indicating an access destination in the network, inaccordance with DNS naming convention.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting/receiving data or is allowed to initiate communicationcontrol when the current PDN connection is the first PDN connection.

More specifically, for example, the UE initiated mode in which the UE 10is allowed to initiate the communication control or the Networkinitiated mode in which the network is allowed to initiate thecommunication control may be identified.

Next, an example of the EPS bearer context for each transfer path and/orbearer will be described with reference to FIG. 10C. As illustrated inFIG. 10C, the context includes at least transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

The Routing access type indicates an access network through which theflow passes. For example, the Routing access type indicates the 3GPP orthe WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The Routing Filter may include an IP header so that the PGW 30 canswitch the IP flow. Alternatively, the Routing Filter may include anapplication ID so that the PGW 30 can switch the flow for eachapplication. Alternatively, the Routing Filter may include a TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule.

FIG. 10D illustrates the TWAG capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether or not capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether or not the TWAG 74 supportsan NBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The PGW 30 may store the NBIFOM capability associated with the TWAG ID.

FIG. 10E illustrates an example of the Network capability. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 10E, the PGW 30 stores the NBIFOM capabilityassociated with the PGW ID. Furthermore, as illustrated in FIG. 10E, theNBIFOM capability may be stored associated with each of the multiplePGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean APN, for example.

The TWAG capability and the Network capability may be included in theEPS bearer context, or may be information separated from the UE context.

2.2.5. PCRF Components

Next, components of the PCRF 60 will be described. FIG. 11 illustrates adevice configuration of the PCRF 60. As illustrated in FIG. 11, the PCRF60 is constituted of an IP mobile communication network interface unit1120, a control unit 1100, and a storage 1140. The IP mobilecommunication network interface unit 1120 and the storage 1140 areconnected to the control unit 1100 via a bus.

The control unit 1100 is a function unit for controlling the PCRF 60.The control unit 1100 implements various processes by reading out andexecuting various programs stored in the storage 1140.

The IP mobile communication network interface unit 1120 is a functionunit through which the PCRF 60 is connected to the PGW 30 and/or theTWAG 74 and/or the AAA 55.

The storage 1140 is a function unit for storing programs, data, and thelike necessary for each operation of the PCRF 60. The storage 940 isconstituted of, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 11, the storage 1140 stores UE context 1142. Notethat the UE context may be classified into a UE context stored for eachUE 10 and a UE context stored for each PDN connection.

FIG. 12A illustrates the UE context for each UE 10. As illustrated inFIG. 12A, the context includes at least a Subscriber ID and a UE NBIFOMcapability. The Subscriber ID is identification information on a user.For example, the subscriber ID may be an IMSI.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether or not capability of establishing the first PDNconnection is supported. In other words, the UE NBIFOM capability isidentification information indicating whether or not the UE 10 supportsthe NBIFOM function. More specifically, for example, the NBIFOMcapability may include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has the function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Next, the UE context for each PDN connection will be described. FIG. 12Billustrates an example of the UE context for each PDN connection. Asillustrated in FIG. 12B, the context may include at least an APN, anOperation mode, a Network Policy, a Charging Rule, a PCC Rule, and a QoSRule.

The APN is a label indicating an access destination in the network, inaccordance with DNS naming convention. The Operation mode isidentification information on a mode that indicates which of the UE 10and the network takes an initiative in transmitting/receiving data or isallowed to initiate communication control when the PDN connection is thefirst PDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be a UE initiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network Policy is a communication control policy on the networkside, and may include the Network allowed mode. Alternatively, the PCRF60 may store the Network allowed mode separately from the NetworkPolicy.

The Charging Rule is a regulation on charging. In accordance with theCharging Rule determined by the PCRF 60, a PCEF performs charging.

The PCC Rule is a regulation relating to control of the Network Policyand Charging Rule. In accordance with the PCC Rule, the PCEF performscommunication control and charging.

The QoS Rule is a regulation relating to QoS of the flow. The QoS Rulemay be associated with the PCC Rule.

FIG. 12C illustrates the UE context for each transfer path and/orbearer. As illustrated in FIG. 12C, the UE context for each transferpath and/or bearer includes at least a Routing Rule.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Based on this association,whether using a communication path through the 3GPP access network orusing a transfer path through the WLAN access network is determined.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the UE 10 and/or the TWAG 74and/or the PGW 30. Alternatively, the Routing Rule may be a value thatthe PCRF 60 prestores as a default value. In this case, the PCRF 60 maydetermine the default value of the Routing Rule in accordance with thePCC Rule.

The Routing Filter may include an IP header so that an IP flow can beswitched. Alternatively, the Routing Filter may include an applicationID so that the flow can be switched for each application. Alternatively,the Routing Filter may include the TFT.

The Routing Rule may store multiple rules. Furthermore, the Routing Rulemay include priority for each rule.

FIG. 12D illustrates an example of the TWAG capability stored by theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether or not capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether or not the TWAG 74 supports an NBIFOM function. Specifically,the NBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in the drawing, the NBIFOM capability may be stored whilebeing associated with the TWAG ID that is the identification informationon the TWAG 74. If not associated with the TWAG ID, the NBIFOMcapability may mean capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored while beingassociated with each other, the PCRF 60 may store the TWAG capability ofmultiple TWAGs 74.

FIG. 12E illustrates an example of the Network capability stored by thePCRF 60. In the Network capability, the NBIFOM capability is stored foreach network, i.e., for each PGW 30.

Here, the NBIFOM capability is identification information indicatingwhether or not capability of establishing the first PDN connection issupported for each network. In other words, the identificationinformation indicates whether or not the PGW 30 supports the NBIFOMfunction. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

2.3. Description of Initial State

An initial state in the present embodiment will be described. Theinitial state in the present embodiment may be a first initial state ora second initial state, both of which will be described later.

Note that the initial state in the present embodiment need not belimited to the first or second initial state.

2.3.1. Description of First Initial State

The first initial state will be described. In the first state, the UE 10has not established the first PDN connection with the core network 90.However, the UE 10 has already established the second PDN connection. Ingreater detail, the UE 10 has not established the first PDN connectionwith the PGW_A 1310. However, the UE 10 has established the second PDNconnection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network B.Thus, the first PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_B 1320. Here, thetransfer path may be a bearer.

As described above, in the first state early stage, the UE 10 may be ina state of being connected to the core network 90 via the access networkB.

Note that the UE 10 need not be connected to the core network 90 via theaccess network A. In other words, the UE 10 need not perform an attachthrough the LTE access network.

Alternatively, the UE 10 may be in a state of being connected to thecore network 90 via the access network A. In this case, the UE 10 mayperform an attach procedure initiated by the UE 10 to establish a thirdPDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The first initial state has been described above; however, the firstinitial state is not limited the above-described state, and only needsto be a state in which the multi-access PDN connection based on theNBIFOM has not been established through the access network B, forexample.

2.3.2. Description of Procedure for Leading to First Initial State

A procedure for leading to the first initial state will be describedwith reference to FIG. 15. In the procedure for leading to the firstinitial state, at least an attach procedure to the core network 90through the access network B, illustrated in (A) of FIG. 15, isperformed. The first initial state is a state after at least the attachprocedure to the core network 90 through the access network B,illustrated in (A) of FIG. 15, is performed.

Next, details of the attach procedure to the core network 90 through theaccess network B will be described. The UE 10 first performsauthentication procedure for accessing the access network B and the corenetwork 90, and a security association procedure for establishing asecurity association to transmit/receive a message to/from the corenetwork 90 (S1502).

In greater detail, the UE 10 performs an authentication procedure foraccessing the TWAG 74 arranged in the access network B and the PGW 30arranged in the core network 90. Based on the completion of theauthentication procedure, the UE 10 performs a procedure forestablishing security associations between the UE 10 and the TWAG 74 andbetween the TWAG 74 and the PGW 30. In the authentication procedure andthe procedure for establishing a security association, the UE 10 maytransmit, to the core network 90, control information including theAccess Point Name (APN). Furthermore, the authentication procedure andthe procedure for establishing the security association may be performedbased on a technique such as the EAP. The UE 10 can obtainauthentication for accessing the PGW 30 selected by the TWAG 74 usingthe APN.

Moreover, the UE 10 may transmit multiple APNs. For example, thetransmission of the APN 1 and the APN 2 will allow the UE 10 to obtain,based on the completion of the authentication procedure and theprocedure for establishing a security association, authentication foraccessing the PGW 30 selected by the TWAG 74 using the APN 1 and the PGW30 selected by the TWAG 74 using the APN 2.

Based on the establishment of the security association, the UE 10performs a PDN connectivity procedure for establishing the second PDNconnection with the core network 90 through the access network B(S1504). In greater detail, the UE 10 establishes, via the TWAG 74, thePDN connection with the PGW_B 1320 arranged in the core network 90.

Specifically, the UE 10 transmits a PDN connectivity request to the TWAG74 and/or the network. The UE 10 may transmit the PDN connectivityrequest including the APN 2.

The TWAG 74 and/or the network receives the PDN connectivity requesttransmitted from the UE 10. Based on the reception of the PDNconnectivity request, the TWAG 74 and/or the network transmits a PDNConnectivity Accept to the UE 10. The TWAG 74 and/or the network maytransmit the PDN Connectivity Accept including the APN 2.

The UE 10 receives the PDN Connectivity Accept transmitted from the TWAG74 and/or the network. Based on the PDN Connectivity Accept, the UE 10transmits a PDN connectivity complete to the TWAG 74 and/or the network.The TWAG 74 and/or the network receives the PDN connectivity completetransmitted from the UE 10.

2.3.3. Description of Second Initial State

A second initial state will be described. In the second initial state,the UE 10 is in a state of not being connected to the core network 90.In other words, the UE 10 has not established either the first PDNconnection or the second PDN connection with the core network 90. Ingreater detail, the UE 10 has not established the first PDN connectionwith the PGW_A 1310 included and arranged in the core network 90.Furthermore, the UE 10 has not established the second PDN connectionwith the PGW_B 1320 included and arranged in the core network 90.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Furthermore, the selection of gateway using the APN 1 and/or the APN2 may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

As described above, the second initial state may be a state in which theUE 10 has no connection with the core network 90. In other words, the UE10 may be in a state of not being connected to the core network 90through either the access network A or access network B. Thus, the UE 10may be in a state in which the PDN connection has not been established.

The second initial state has been described above; however, the secondinitial state is not limited to the above-described state, and onlyneeds to be a state in which the connection to the core network 90through the access network B has not been established, for example.

2.3.4. Description of Procedure for Leading to Second Initial State

A procedure for leading to the second initial state will be describedwith reference to FIG. 15. The procedure for leading to the secondinitial state may be a state in which the procedure illustrated in (A)of FIG. 15 is not performed. In other words, the second initial statemay be a state in which a special procedure for connecting to the corenetwork 90 through the access network B is not performed at all. Thatis, the second initial state may be a state in which the UE 10 performsinitial connection to the core network 90 through the access network B.

2.3.5. Description of Multi-Access PDN Connectivity EstablishmentProcedure

Next, an establishment procedure of the first PDN connection will bedescribed. Here, the initial state may be the first initial state or thesecond initial state. In the present embodiment, after the establishmentof the initial state, the UE 10 performs a PDN connectivity procedurefor establishing the first PDN connection with the core network 90through the access network B (S1506). In greater detail, the UE 10establishes, via the TWAG 74, the first PDN connection with the PGW_A1310 arranged in the core network 90.

Note that the first PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_A 1310. Here, thetransfer path may be a bearer.

As illustrated in FIG. 15, the procedure for establishing the first PDNconnection may be a PDN connectivity procedure using the APN 1. Aspecific example of the PDN connectivity procedure will be describedbelow.

2.4. Examples of PDN Connectivity Procedure

An example of the PDN connectivity procedure for establishing the firstPDN connection will be described with reference to FIG. 16.

2.4.1. Example of First PDN Connectivity Procedure

An example of the first PDN connectivity procedure will be describedwith reference to FIG. 16.

As illustrated in (B) of FIG. 16, the UE 10 first performs theauthentication procedure and the security association procedure forestablishing the security association. Note that the UE 10 may performthe security association procedure when the initial state is the secondinitial state. In other words, the UE 10 need not perform the securityassociation procedure when the initial state is the first initial state.As described above, when the initial state is the first initial state,the UE 10 may omit the security association procedure since the securityassociation has already been established.

Note that the security association procedure performed by the UE 10 maybe similar to the security association procedure described in (A) ofFIG. 15. Therefore, detailed description of the procedure will beomitted.

Next, the UE 10 transmits a PDN connectivity request to the TWAG 74(S2102). The UE 10 may transmit the PDN connectivity request includingat least the PDN connectivity request message ID (PDN connectivityrequest message identity), the procedure transaction ID (Proceduretransaction identity), the request type (Request type), and the PDNtype. Furthermore, the UE 10 may include at least the firstidentification information and/or sixth identification information inthe PDN connectivity request. Moreover, the UE 10 may include the AccessPoint Name (APN) and/or Protocol Configuration Options (PCOs) and/or theTraffic Flow Templates (TFTs) in the PDN connectivity request. Note thatthe UE 10 may transmit the PCO including the first identificationinformation and/or the sixth identification information and/or the TFT.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the possession ofthe function of establishing the multi-access PDN connection based onthe NBIFOM.

In addition, the sixth identification information may be a RequestNBIFOM representing a request to determine the NBIFOM operation mode forthe multi-access PDN connection based on the NBIFOM.Additionally/alternatively, the sixth identification information may beinformation representing that a request for an NBIFOM operation modeallowed for the multi-access PDN connection based on the NBIFOM to beestablished.

As described above, the UE 10 may transmit the PDN connectivity requestincluding the first identification information and/or sixthidentification information to request the establishment of themulti-access PDN connection based on the NBIFOM, without requesting aspecific NBIFOM operation mode.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message. The proceduretransaction ID may be information for identifying the PDN connectivityprocedure.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1,in order to establish the multi-access PDN connection based on theNBIFOM. Here, the APN 1 may be an APN that is allowed to establish themulti-access PDN connection based on the NBIFOM and/or an APN that isallowed to perform communication based on the NBIFOM.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6. The PCO may be protocol informationassociated with the PDN connection. Furthermore, the PCO may includeidentification information on the request. Note that the UE 10 maytransmit the PCO including the first identification information and/orthe sixth identification information.

The TFT may be information for identifying an IP flow that performscommunication by using the PDN connection established in the present PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, by the TFT, user data of a specificapplication can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a specific NBIFOM operation mode,and thus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection based on the NBIFOMwithout requesting a specific NBIFOM operation mode, the UE 10 maytransmit the PDN connectivity request without including the TFT. Morespecifically, when the UE 10 includes the first identificationinformation and/or the sixth identification information, the UE 10 maytransmit the PDN connectivity request without including the TFT. Notethat in the related art, the UE 10 can perform transmission, withinformation indicating the IFOM support included in the PCO. Here, theIFOM support is identification information representing that the IP FlowMobility (IFOM) is supported. Furthermore, the IFOM is a technique forswitching a communication path of a specific IP flow by using the DualStack Mobile IPv6 (DSMIPv6) protocol. Thus, including the informationindicating the IFOM support in the PCO allows the UE 10 to switch theaccess network through which the communication of a specific IP flow isperformed.

In the present embodiment, when the UE 10 includes the firstidentification information and the sixth identification information inthe PCO, the UE 10 does not include the IFOM support. In contrast, whenthe UE 10 includes the IFOM support in the PCO, the UE 10 does notinclude the first identification information and/or the sixthidentification information. As described above, it may be possible tonot configure both the first identification information and/or sixthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 can establish either the PDN connection supporting theIFOM or the PDN connection supporting the NBIFOM, in the establishmentprocedure of a single PDN connection. In other words, the single PDNconnection is any one of the PDN connection supporting the NBIFOM, thePDN connection supporting the IFOM, or the single-access PDN connection.

The TWAG 74 receives the PDN connectivity request transmitted from theUE 10. Based on the reception of the PDN connectivity request and/or thefirst identification information and/or sixth identification informationincluded in the PDN connectivity request, the TWAG 74 transmits a CreateSession Request to the PGW 30 (S2104).

Based on the reception of the PDN connectivity request and/or the firstidentification information and/or sixth identification informationincluded in the PDN connectivity request, the TWAG 74 may transmit theCreate Session Request including at least the first identificationinformation and/or sixth identification information. Furthermore, theTWAG 74 may include the TFT in the Create Session Request, based on thereception of the TFT transmitted from the UE 10.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the PDN connectivityrequest, the TWAG 74 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the TWAG 74 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the TWAG74. Based on the reception of the Create Session Request, and/or thefirst identification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure with the PCRF 60.

Based on the reception of the Create Session Request and/or the firstidentification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure including at least the firstidentification information and/or the sixth identification information.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or TWAG 74.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection based onthe NBIFOM or the single-access PDN connection, and/or the sixthidentification information.

More specifically, when the multi-access PDN connection based on theNBIFOM is to be established, the PGW 30 transmits, to the PCRF 60, theinformation indicating the access network B, the PDN connection ID, theinformation indicating that the PDN connection is the multi-access PDNconnection based on the NBIFOM, and the first identification informationand/or sixth identification information. Alternatively, when thesingle-access PDN connection is to be established, the PGW 30 transmits,to the PCRF 60, the information indicating the access network B, the PDNconnection ID, and the information indicating that the PDN connection isthe single-access PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, based on the reception of the first identificationinformation and/or sixth identification information, the PCRF 60 maytransmit, to the PGW 30, a control message in the IP-CAN session updateprocedure with the PGW 30, the control message including at least theseventh identification information. The detailed description of theseventh identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 transmits aCreate Session Response to the TWAG 74 (S2106).

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 may transmitthe Create Session Response including at least the seventhidentification information.

Furthermore, the PGW 30 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in the Create Session Response.

Note that a method by which the PGW 30 acquires the seventhidentification information is not limited to the above-described methodfor acquiring the seventh identification information from the PCRF 60 inthe IP-CAN session update procedure, and another example may beemployed. For example, the PGW 30 may create the seventh identificationinformation and transmit the Create Session Response including theseventh identification information, without acquiring the seventhidentification information from the PCRF 60 in the IP-CAN session updateprocedure.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection based on the NBIFOM to be established. Inother words, the seventh identification information may be the operationmode allowed by the operator.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode orthe seventh identification information based on the operator policy. Forexample, a policy that allows for the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows for theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows for the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

Based on the Allowed Mode, the PCRF 60 or the PGW 30 may include theallowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both of the UE-Initiated mode and the Network-Initiatedmode are allowed, the seventh identification information may includeboth the operation modes. Alternatively, when both of the UE-Initiatedmode and the Network-Initiated mode are allowed and a default operationmode is configured, the seventh identification information may includeonly the default operation mode. Note that which of the UE-Initiatedmode and the Network-Initiated mode is defined as the default operationmode may be configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the Requested Operation Mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the TWAG 74 of the seventhidentification information.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may transmit, to the TWAG 74, the Create SessionResponse including the cause information indicating that the RequestedOperation Mode is not allowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the TWAG 74 that there is no allowedoperation.

As described above, based on the Allowed Mode, the PCRF 60 or the PGW 30may regard an operation mode that is allowed for establishment of thePDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theTWAG 74. Thus, in this case, the PGW 30 need not include either the TFTor the PDN address (PDN Address) in the Create Session Response.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PGW 30 maytransmit the TFT to the TWAG 74. Thus, in this case, the PGW 30 mayinclude the TFT and the PDN address (PDN Address) in the Create SessionResponse.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the TWAG 74. In other words, the PGW 30 may assign the PDNconnection ID.

The TWAG 74 receives the Create Session Response transmitted from thePGW 30. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the TWAG 74 transmits a PDN Connectivity Accept to the UE 10(S2108).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theTWAG 74 may transmit the PDN Connectivity Accept including at least aPDN Connectivity Accept message ID (PDN Connectivity Accept messageidentity), the procedure transaction ID, the APN, the PDN address (PDNAddress), the PDN connection ID, and the user plane connection ID (UserPlane Connection ID). Furthermore, the TWAG 74 may include at least theseventh identification information in the PDN Connectivity Accept.Moreover, the TWAG 74 may include the PCO and/or the Cause and/or theTFT and/or PDN connection attribute information, in the PDN ConnectivityAccept. Note that the TWAG 74 may transmit the PCO including the seventhidentification information and/or the TFT.

Here, the PDN Connectivity Accept message ID may be a message typerepresenting the PDN Connectivity Accept message.

The APN may be an APN to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection based on theNBIFOM. The TWAG 74 may include the APN 1 in the PDN ConnectivityAccept.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The PDN connection ID may be information for uniquely identifying thePDN connection established between the UE 10 and the PGW 30. The PDNconnection ID may be an ID assigned by the PGW 30, or an ID assigned bythe TWAG 74. In other words, the TWAG 74 may assign the PDN connectionID.

The user plane connection ID is information for identifying a userplane. The user plane is a transfer path used for transferring user datain the PDN connection. The TWAG 74 may assign the user plane connectionID.

The Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the TWAG 74 and/or the PGW 30 may include the seventhidentification information in the PCO. However, when the TWAG 74 and/orthe PGW 30 includes the seventh identification information in the PCO,the TWAG 74 and/or the PGW 30 does not include the IFOM support. Incontrast, when the TWAG 74 and/or the PGW 30 includes the IFOM supportin the PCO, the TWAG 74 and/or the PGW 30 does not include the seventhidentification information. As described above, it may be possible tonot configure both the seventh identification information and the IFOMsupport to be effective to ensure a clear distinction between the use ofthe switching of the communication path based on the NBIFOM and the useof the switching of the communication path based on the IFOM.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted/received by using the PDNconnection established in the PDN connectivity procedure is allowed tobe transmitted/received through the access network A and the accessnetwork B, and/or information indicating that the PDN connectionestablished in the present PDN connectivity procedure is themulti-access PDN connection based on the NBIFOM of the operation modeindicated by the seventh identification information when there is onlyone operation mode indicated by the seventh identification information.

Note that the UE 10 may transmit the PDN Connectivity Accept messagethat further includes the connectivity type indicating the type of thePDN connection and/or the WLAN offload permission information (WLANoffload acceptability) indicating whether or not the WLAN offload can beperformed. Furthermore, the TWAG 74 may transmit the connectivity typeor the WLAN offload permission information including the PDN connectionattribute information.

The UE 10 receives the PDN Connectivity Accept transmitted from the TWAG74. Based on the reception of the PDN Connectivity Accept and/or theseventh identification information included in the PDN ConnectivityAccept, the UE 10 transmits a PDN connectivity complete to the TWAG 74(S2110).

The UE 10 may transmit the PDN connectivity complete including at leastthe PDN connectivity complete message ID (PDN connectivity complete),the procedure transaction ID, and the PDN connection ID.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the PDN connectivity complete. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in thePDN Connectivity Accept, the UE 10 may include the UE-Initiated mode orthe Network-Initiated mode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

The PDN connectivity complete message ID may be a message typerepresenting the PDN connectivity complete message.

After the fourth PDN connectivity procedure is completed, the UE 10 andthe PGW 30 establish the first PDN connection of the operation modedetermined based on the operator policy. Alternatively, the UE 10establishes the first PDN connection of an operation mode selected fromthe operation modes allowed based on the operator policy. Note that theUE 10 may identify the NBIFOM operation mode for the established PDNconnection, based on the reception of the PDN Connectivity Accept,and/or the PDN connection attribute information and/or the seventhidentification information and/or the operation mode selected based onthe seventh identification information. Based on the establishment ofthe first PDN connection, the UE 10 and the PGW 30 determine a PDNconnection and/or a transfer path (such as an EPS bearer) fortransmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT. More specifically, the UE 10 and the PGW 30 transmit/receive aflow identified by the TFT by using the first PDN connection.

Note that in the example of the first PDN connectivity procedure, a casehas been described in which the transmission/reception of the TFT isincluded in the PDN connectivity procedure; however, the first PDNconnectivity procedure is not limited to this case. Thetransmission/reception of the TFT may be performed after themulti-access PDN connection based on the NBIFOM is established.

Therefore, the UE 10 and the TWAG 74 may perform transmission/receptionwithout including the TFT in the PDN connectivity request and/or the PDNconnectivity response (PDN Connectivity Accept), and establish themulti-access PDN connection based on the NBIFOM. In other words, at apoint in time when the PDN connection is established, there may be no IPflow transmitting/receiving user data by using the PDN connection. Inthis case, the UE 10 and the TWAG 74 transmit the TFT after themulti-access PDN connection based on the NBIFOM is established.

More specifically, when the PDN connection of the UE-Initiated mode isestablished, the UE 10 may transmit the TFT to the TWAG 74. In addition,the TWAG 74 receives the TFT from the UE 10 and transmits the TFT to thePGW 30. Thus, the UE 10 and the PGW 30 can determine a PDN connectionand/or a transfer path (such as an EPS bearer) fortransmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT.

On the other hand, when the PDN connection of the Network-Initiated modeis established, the PGW 30 may transmit the TFT to the TWAG 74. Here,the PGW 30 may receive, from the PCRF 60, the TFT determined based onthe operator policy. In addition, the TWAG 74 receives the TFT from thePGW 30 and transmits the TFT to the UE 10. Thus, the UE 10 and the PGW30 can determine a PDN connection and/or a transfer path (such as an EPSbearer) for transmitting/receiving the IP flow by using the TFT, andtransmit/receive user data corresponding to the IP flow identified bythe TFT.

Furthermore, in the example of the first PDN connectivity procedure, acase has been described in which the UE 10 and the PGW 30 establish thefirst PDN connection of an operation mode selected by the UE 10 from theoperation modes determined based on the operator policy or the operationmodes allowed based on the operator policy; however, the first PDNconnectivity procedure is not limited to this case. The UE 10 may rejectthe establishment of the first PDN connection.

For example, when the UE 10 does not support the operation mode allowedbased on the operator policy and/or when the operation mode allowedbased on the operator policy does not comply with the policy of the UE10, the UE 10 may reject the establishment of the first PDN connection.

In greater detail, the UE 10 may transmit a PDN connectivity reject tothe TWAG 74, based on the reception of the PDN Connectivity Acceptand/or the seventh identification information included in the PDNConnectivity Accept and/or the PDN connection attribute informationand/or the policy of the UE 10.

The UE 10 may transmit the PDN connectivity reject including at leastone or more of a PDN connectivity reject message ID (PDN connectivityreject message identity), the procedure transaction ID, and the Cause.Furthermore, the UE 10 may further include fourth identificationinformation in the PDN connectivity reject. Moreover, the UE 10 mayfurther include the PCO and/or the Tw1 value in the PDN connectivityreject. Note that the UE 10 may transmit the PCO including the fourthidentification information.

The fourth identification information may be information representingthat the UE 10 does not support the operation mode allowed based on theoperator policy and/or information representing that the operation modeallowed based on the operator policy does not comply with the policy ofthe UE 10.

The PDN connectivity reject message ID may be a message typerepresenting the PDN connectivity reject message.

The Cause may be information representing a reason why the PDNconnectivity request is rejected. Here, the UE 10 may notify the UE 10of the fourth identification information included in the Cause.

The Tw1 value may be a value of the Tw1 timer, included when the Causerepresents insufficient resources.

The TWAG 74 may receive the PDN connectivity reject transmitted from theUE 10. Based on the reception of the PDN connectivity reject and/or thefourth identification information included in the PDN connectivityreject, the TWAG 74 may delete the EPS bearer context, held by the TWAG74, relating to the established PDN connection. Furthermore, the TWAG 74may transmit, to the PGW 30, the fourth identification informationincluded in the PDN connectivity reject.

The PGW 30 may receive the fourth identification information transmittedfrom the TWAG 74. Based on the reception of the fourth identificationinformation and/or the operator policy, the PGW 30 may delete the EPSbearer context, held by the PGW 30, relating to the established PDNconnection.

Furthermore, the PGW 30 may perform the IP-CAN session update procedurewith the PCRF 60, based on the reception of the fourth identificationinformation. The PGW 30 may include the fourth identificationinformation in the IP-CAN session update procedure.

The PCRF 60 may change the operator policy based on the IP-CAN sessionupdate procedure. Note that based on the change of the operator policy,the PGW 30 may delete the EPS bearer context, held by the PGW 30,relating to the established PDN connection.

2.4.2. Description of State after PDN Connectivity EstablishmentProcedure

Performing the above-described first to seventh PDN connectivityprocedures leads to a first state and a second state, both of which willbe described later.

Note that an initial state in the additional attach procedure may be thefirst state or the second state. Note that the initial state in theadditional attach procedure may not be limited to the first or secondstate.

2.4.3. Description of First State

The first state will be described with reference to FIG. 13. In thefirst state, the UE 10 has established the first PDN connection with thecore network 90. However, the UE 10 has not yet established the secondPDN connection. In greater detail, the UE 10 has established the firstPDN connection with the PGW_A 1310. However, the UE 10 has notestablished the second PDN connection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection based on the NBIFOM is establishedvia the access network B. In addition, in the first state early stage,the UE 10 may be in a state of not being connected to the core network90 via the access network A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The first state has been described above; however, the first state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection based on the NBIFOM has beenestablished through the access network B and the PDN connection has notbeen established through the access network A, for example.

2.4.4. Description of Second State

The second state will be described with reference to FIG. 14. In thesecond state, the UE 10 has established the first PDN connection withthe core network 90. Furthermore, the UE 10 has established the secondPDN connection with the core network 90. In greater detail, the UE 10has established the first PDN connection with the PGW_A 1310.Furthermore, the UE 10 has established the second PDN connection withthe PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_B 1320. Here, the transferpath may be a bearer.

In addition, the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network A.Thus, the second PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and theeNodeB 45, a transfer path between the eNodeB 45 and the SGW 35, and atransfer path between the SGW 35 and the PGW_B 1320. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection based on the NBIFOM is establishedvia the access network B. Furthermore, the UE 10 may be in a state inwhich the single-access PDN connection is established via the accessnetwork A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using another APN differentfrom the APN 1 and the APN 2.

The second state has been described above; however, the second state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection based on the NBIFOM has beenestablished through the access network B and the single-access PDNconnection has been established through the access network A, forexample.

2.5. Additional Attach Procedure

Hereinafter, an additional attach procedure will be described. The factthat the Operation mode of the first PDN connection is theNetwork-initiated mode means that, in other words, the UE 10 cannotinitiate the switching of the flow and/or the update of the routing ruleof the PDN connection. On the other hand, the PDN connectivity procedureand/or the attach procedure is initiated by the UE 10.

As discussed above, the second state is a state in which the UE 10 hasestablished the first PDN connection through only the access network B.That is, a transfer path through the LTE access network is not includedin the first PDN connection. Note that the transfer path may be a bearerand/or a communication path.

Accordingly, when the first PDN connection of the second state is in theNetwork-initiated mode, the network and/or the PCRF 60 cannot include atransfer path through the access network A in the first PDN connection.

As such, the UE 10 may execute a procedure to establish a transfer paththrough the access network A, based on the state transition to thesecond state and the Operation mode being in the Network-initiated mode.

Further, also in the case where the Operation mode of the first PDNconnection of the first initial state and/or the second initial state isthe UE-initiated mode, the UE 10 may perform the establishment procedureof a transfer path through the access network A based on the routingrule stored by the UE 10.

To be specific, in the case where the routing rule of the first PDNconnection indicates that the LTE access is prioritized, the UE 10 mayexecute a procedure to add, to the first PDN connection, a transfer paththrough the access network A.

To be more specific, in the case where the UE 10 stores a routing ruleassociating a specific flow with the LTE access for the first PDNconnection, the UE 10 may execute the procedure to add a transfer paththrough the access network A.

To rephrase, in the case where the routing rule of the first PDNconnection does not indicate that the LTE access is prioritized, the UE10 does not execute the procedure to add, to the first PDN connection, atransfer path through the access network A.

To be more specific, in the case where the UE 10 does not store arouting rule associating a specific flow with the LTE access for thefirst PDN connection, the UE 10 does not execute the procedure to add atransfer path through the access network A.

Details of the procedure will be described below.

2.5.1 Example of Second Additional Attach Procedure

An example of a second additional attach procedure will be describednext. As illustrated in the drawing, the initial state of the example ofthe present procedure is the first initial state (S2302). A procedure totransition to the first initial state may be similar to theaforementioned procedure, and detailed description thereof is omittedherein.

It is sufficient for the first initial state to be a state in which theUE 10 has established the first PDN connection with the PGW 30 and/orthe network through the access network A. Specifically, the firstinitial state is a state in which the UE 10 has established the firstPDN connection, through the TWAG 74, with the PGW_A selected by usingthe APN 1. The first PDN connection may be the multi-access PDNconnection based on the NBIFOM.

The UE 10 performs the attach procedure through the access network A(S2304) based on having transitioned to the first initial state andhaving established the first PDN connection in the Network-initiatedmode.

Alternatively, the UE 10 may perform the attach procedure through theaccess network A, based on having transitioned to the first initialstate in which the first PDN connection has been established in theUE-initiated mode and based on the routing rule.

To be specific, based on the fact that the routing rule prioritizes theLTE access, the UE 10 may perform the attach procedure through theaccess network A.

Specifically, the UE 10 may perform the attach procedure through theaccess network A in the case where the transition to the first state hasbeen made in which the first PDN connection in the UE-initiated mode hasbeen established and the routing rule of the first PDN connectionindicates that the LTE access is prioritized.

More specifically, the UE 10 may perform the attach procedure throughthe access network A in the case where the transition to the firstinitial state has been made in which the first PDN connection in theUE-initiated mode has been established and the UE 10 stores the routingrule associating a specific flow with the LTE access for the first PDNconnection.

In other words, the UE 10 does not perform the attach procedure throughthe access network A in the case where the routing rule of the first PDNconnection does not indicate that the LTE access is prioritized, even ifthe transition to the first initial state has been made in which thefirst PDN connection in the UE-initiated mode has been established.

More specifically, the UE 10 does not perform the attach procedurethrough the access network A, even if the transition to the firstinitial state has been made in which the first PDN connection in theUE-initiated mode has been established, in the case where the UE 10 doesnot store the routing rule associating a specific flow with the LTEaccess for the first PDN connection.

The attach procedure through the access network A may be the same as theattach procedure described with reference to FIG. 45 in Chapter XX, andtherefore detailed description thereof will be omitted herein.

Note that, however, the UE 10 may transmit an attach request includingat least an APN and/or PDN connection ID.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2,in order to establish a single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish a multi-access PDNconnection based on the NBIFOM and/or an APN that is not allowed toperform communication based on the NBIFOM.

That is, the UE 10 may request the establishment of the single-accessPDN connection using the APN 2 different from the APN 1 acquired fromthe network when the first PDN connection is established.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

The UE 10 performs, during the attach procedure, an authenticationprocedure and a security association procedure with the MME 40, thePGW_A, and the PGW_B. Based on the completion of the attach procedure,the UE 10 may acquire the APN from the network.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2,in order to establish a single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish a multi-access PDNconnection based on the NBIFOM and/or an APN that is not allowed toperform communication based on the NBIFOM.

That is, the UE 10 may establish the single-access PDN connection usingthe APN 2 different from the APN 1 acquired from the network based onthe establishment of the first PDN connection.

In the manner discussed above, the UE 10 and the core network 90transition from the first initial state to the second initial state(S2306).

Next, the UE 10 performs the PDN connectivity procedure through theaccess network A (S2308) based on having transitioned to the secondinitial state and the first PDN connection having been established inthe Network-initiated mode.

Alternatively, the UE 10 may perform the PDN connectivity procedurethrough the access network A based on having transitioned to the secondinitial state and based on the routing rule of the first PDN connectionhaving been established in the UE-initiated mode.

To be specific, based on the fact that the routing rule prioritizes theLTE access, the UE 10 may perform the attach procedure through theaccess network A.

Specifically, the UE 10 may execute a procedure to add a transfer path,through the access network A, in the first PDN connection in the casewhere the transition to the second initial state has been made in whichthe first PDN connection in the UE-initiated mode has been establishedand the routing rule of the first PDN connection indicates that the LTEaccess is prioritized.

More specifically, the UE 10 may execute the procedure to add a transferpath through the access network A in the case where the transition tothe second initial state has been made in which the first PDN connectionin the UE-initiated mode has been established and the UE 10 stores therouting rule associating a specific flow with the LTE access for thefirst PDN connection.

In other words, the UE 10 does not execute the procedure to add atransfer path, through the access network A, in the first PDNconnection, even if the transition to the second initial state has beenmade in which the first PDN connection in the UE-initiated mode has beenestablished, in the case where the routing rule of the first PDNconnection does not indicate that the LTE access is prioritized.

More specifically, the UE 10 does not execute the procedure to add atransfer path through the access network A, even if the transition tothe second initial state has been made in which the first PDN connectionin the UE-initiated mode has been established, in the case where the UE10 does not store the routing rule associating a specific flow with theLTE access for the first PDN connection. The PDN connectivity procedurethrough the access network A will be described with reference to FIG.18.

First, the UE 10 transmits a PDN connectivity request to the MME 40through the eNodeB 45 (S2402). The UE 10 may transmit the PDNconnectivity request including at least the PDN connectivity requestmessage ID (PDN connectivity request message identity), the proceduretransaction ID (Procedure transaction identity), the request type(Request type), the PDN type, the protocol discriminator (Protocoldiscriminator), and the EPS bearer ID (EPS bearer identity).Furthermore, the UE 10 may include at least the first identificationinformation and/or sixth identification information and/or the PDNconnection ID in the PDN connectivity request. Moreover, the UE 10 mayinclude the Access Point Name (APN) and/or Protocol ConfigurationOptions (PCOs) and/or the Traffic Flow Templates (TFTs) in the PDNconnectivity request. Note that the UE 10 may transmit the PCO includingthe first identification information and/or the sixth identificationinformation and/or the TFT and/or the PDN connection ID.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the possession ofthe function of establishing the multi-access PDN connection based onthe NBIFOM.

In addition, the sixth identification information may be a RequestNBIFOM representing that a request to determine the NBIFOM operationmode for the multi-access PDN connection based on the NBIFOM.Additionally/alternatively, the sixth identification information may beinformation representing that a request for an NBIFOM operation modeallowed for the multi-access PDN connection based on the NBIFOM to beestablished.

As described above, the UE 10 may transmit the PDN connectivity requestincluding the first identification information and/or sixthidentification information to request the establishment of themulti-access PDN connection based on the NBIFOM, without requesting aspecific NBIFOM operation mode.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message. The proceduretransaction ID may be information for identifying the PDN connectivityprocedure.

The APN may be an APN to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1,in order to establish the multi-access PDN connection based on theNBIFOM. Here, the APN 1 may be an APN that is allowed to establish themulti-access PDN connection based on the NBIFOM and/or an APN that isallowed to perform communication based on the NBIFOM. Further, the APNmay be identification information for identifying the first PDNconnection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30. Further, the PDN connection ID may beidentification information for identifying the first PDN connection. ThePDN connection ID may be associated with the APN.

Note that the UE 10 may identify the first PDN connection by using theAPN and/or the PDN connection ID.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The protocol discriminator may be a discriminator representing the typeof the protocol used when transmitting/receiving the PDN connectivityrequest. The EPS bearer ID may be information for identifying the EPSbearer. The EPS bearer ID may be assigned by the MME 40.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or the sixth identification information.

The TFT may be information for identifying an IP flow that performscommunication by using the PDN connection established in the present PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, by the TFT, user data of a specificapplication can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a specific NBIFOM operation mode,and thus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection based on the NBIFOMwithout requesting a specific NBIFOM operation mode, the UE 10 maytransmit the PDN connectivity request without including the TFT. Morespecifically, when the UE 10 includes the first identificationinformation and/or the sixth identification information, the UE 10 maytransmit the PDN connectivity request without including the TFT.

Note that in the related art, the UE 10 can perform transmission, withinformation indicating the IFOM support included in the PCO. Here, theIFOM support is identification information representing that the IP FlowMobility (IFOM) is supported. Furthermore, the IFOM is a technique forswitching a communication path of a specific IP flow by using an interDual Stack Mobile IPv6 (DSMIPv6) protocol. Thus, including theinformation indicating the IFOM support in the PCO allows the UE 10 toswitch the access network through which the communication of a specificIP flow is performed.

In the present embodiment, when the UE 10 includes the firstidentification information and the sixth identification information inthe PCO, the UE 10 does not include the IFOM support. In contrast, whenthe UE 10 includes the IFOM support in the PCO, the UE 10 does notinclude the first identification information and/or the sixthidentification information. As described above, it may be possible tonot configure both the first identification information and/or sixthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 can establish either the PDN connection supporting theIFOM or the PDN connection supporting the NBIFOM, in the establishmentprocedure of a single PDN connection. In other words, the single PDNconnection is any one of the PDN connection supporting the NBIFOM, thePDN connection supporting the IFOM, or the single-access PDN connection.

The MME 40 receives the PDN connectivity request transmitted from the UE10. Based on the reception of the PDN connectivity request, and/or thefirst identification information included in the PDN connectivityrequest as well as the sixth identification information included in thePDN connectivity request, the MME 40 transmits a Create Session Requestto the SGW 35 (S2404).

Based on the reception of the PDN connectivity request and/or the firstidentification information included in the PDN connectivity request, theMME 40 may transmit the Create Session Request including at least thefirst identification information.

Based on the reception of the PDN connectivity request and/or the sixthidentification information included in the PDN connectivity request, theMME 40 may transmit the Create Session Request including at least thesixth identification information. Furthermore, the MME 40 may includethe TFT in the Create Session Request, based on the reception of the TFTtransmitted from the UE 10.

Furthermore, the MME 40 may include the APN and/or the PDN connection IDin the Create Session Request, based on the reception of the APN and/orthe PDN connection ID transmitted from the UE 10. Note that the MME 40may identify the first PDN connection by using the APN and/or the PDNconnection ID having been received.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the PDN connectivityrequest, the MME 40 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the MME 40 may execute a procedure forestablishing the single-access PDN connection.

The SGW 35 receives the Create Session Request transmitted from the MME40. Based on the reception of the session connectivity request, and/orthe first identification information and/or sixth identificationinformation included in the session connectivity request, the SGW 35transmits the Create Session Request to the PGW 30 (S2206).

Based on the reception of the session connectivity request, and/or thefirst identification information and/or sixth identification informationincluded in the session connectivity request, the SGW 35 may transmitthe Create Session Request including at least the first identificationinformation and/or sixth identification information. Further, the SGW 35may include the TFT in the Create Session Request.

Furthermore, the SGW 35 may include the APN and/or the PDN connection IDin the Create Session Request, based on the reception of the APN and/orthe PDN connection ID transmitted from the MME 40. Note that the SGW 35may identify the first PDN connection by using the APN and/or the PDNconnection ID having been received.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thepresent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, by the TFT, user data ofa specific application can be identified.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that when neither the first identification information nor thesixth identification information is included in the Create SessionRequest, the SGW 35 may transmit the Create Session Request withoutincluding the first identification information and/or the sixthidentification information. Moreover, when the first identificationinformation and/or the sixth identification information is not includedin the PDN connectivity request, the MME 40 may execute a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the SGW35. Based on the reception of the Create Session Request, and/or thefirst identification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure with the PCRF 60 (S2408).

Based on the reception of the Create Session Request and/or the firstidentification information and/or sixth identification informationincluded in the Create Session Request, the PGW 30 may perform theIP-CAN session update procedure including at least the firstidentification information and/or the sixth identification information.

Further, the PGW 30 may identify the first PDN connection by using theAPN and/or the PDN connection ID having been received, based on thereception of the APN and/or the PDN connection ID transmitted from theSGW 35.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or the eNodeB 45and/or the MME 40 and/or the SGW 35.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection based onthe NBIFOM or the single-access PDN connection, and/or the firstidentification information, and/or the sixth identification information.

More specifically, when the multi-access PDN connection based on theNBIFOM is to be established, the PGW 30 transmits, to the PCRF 60, theinformation indicating the access network A, the PDN connection ID, theinformation indicating that the PDN connection is the multi-access PDNconnection based on the NBIFOM, and the first identification informationand/or sixth identification information. Alternatively, when thesingle-access PDN connection is to be established, the PGW 30 transmits,to the PCRF 60, the information indicating the access network A, the PDNconnection ID, and the information indicating that the PDN connection isthe single-access PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, based on the reception of the first identificationinformation and/or sixth identification information, the PCRF 60 maytransmit, to the PGW 30, a control message in the IP-CAN session updateprocedure with the PGW 30, the control message including at least theseventh identification information. The detailed description of theseventh identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 transmits aCreate Session Response to the SGW 35 (S2410).

Based on the reception of the Create Session Request or the completionof the IP-CAN session update procedure, and/or the first identificationinformation and/or sixth identification information included in theCreate Session Request and/or the seventh identification informationincluded in the IP-CAN session update procedure, the PGW 30 may transmitthe Create Session Response including at least the seventhidentification information.

Furthermore, the PGW 30 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in the Create Session Response.

Note that a method by which the PGW 30 acquires the seventhidentification information is not limited to the above-described methodfor acquiring the seventh identification information from the PCRF 60 inthe IP-CAN session update procedure, and another example may beemployed. For example, the PGW 30 may create the seventh identificationinformation and transmit the Create Session Response including theseventh identification information, without acquiring the seventhidentification information from the PCRF 60 in the IP-CAN session updateprocedure.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection based on the NBIFOM to be established. Inother words, the seventh identification information may be the operationmode allowed by the operator.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode orthe seventh identification information based on the operator policy. Forexample, a policy that allows for the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows for theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows for the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

Based on the Allowed Mode, the PCRF 60 or the PGW 30 may include theallowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both of the UE-Initiated mode and the Network-Initiatedmode are allowed, the seventh identification information may includeboth the operation modes. Alternatively, when both of the UE-Initiatedmode and the Network-Initiated mode are allowed and a default operationmode is configured, the seventh identification information may includeonly the default operation mode. Note that which of the UE-Initiatedmode and the Network-Initiated mode is defined as the default operationmode may be configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the Requested Operation Mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the MME 40 of the seventhidentification information through the SGW 35.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may transmit, to the MME 40 through the SGW 35,the Create Session Response including the cause information indicatingthat the Requested Operation Mode is not allowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the MME 40 through the SGW 35 thatthere is no allowed operation.

As described above, based on the Allowed Mode, the PCRF 60 or the PGW 30may regard an operation mode that is allowed for establishment of thePDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theMME 40 through the SGW 35. Thus, in this case, the PGW 30 need notinclude either the TFT or the PDN address in the Create SessionResponse.

In other words, only when the Network-Initiated mode is included in theseventh identification information, the PGW 30 may transmit the TFT tothe MME 40 through the SGW 35. Thus, in this case, the PGW 30 mayinclude the TFT and the PDN address (PDN Address) in the Create SessionResponse.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the MME 40. In other words, the PGW 30 may assign the PDNconnection ID.

The SGW 35 receives the Create Session Response transmitted from the PGW30. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the SGW 35 transmits the Create Session Response to the MME 40(S2412).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theSGW 35 may transmit the Create Session Response including at least theseventh identification information.

Furthermore, the SGW 35 may include the PDN address (PDN Address) and/orthe PDN connection ID and/or the TFT in the session request response.

The MME 40 receives the Create Session Response transmitted from the SGW35. Based on the reception of the Create Session Response and/or theseventh identification information included in the Create SessionResponse, the MME 40 transmits an activated default EPS bearer contextrequest (Activated default EPS bearer context request) to the eNodeB 45(S2414).

Based on the reception of the Create Session Response and/or the seventhidentification information included in the Create Session Response, theMME 40 may transmit the activated default EPS bearer context requestincluding at least an activated default EPS bearer context requestmessage ID (Activated default EPS bearer context request messageidentity), the procedure transaction ID, the APN, the PDN address (PDNAddress), the protocol discriminator, the EPS bearer ID, and the EPSQoS. Further, the MME 40 may include at least the seventh identificationinformation in the activated default EPS bearer context request.Furthermore, the MME 40 may include the PCO and/or the ESM Cause and/orthe TFT and/or the PDN connection ID and/or the PDN connection attributeinformation in the activated default EPS bearer context request. Notethat the MME 40 may transmit the PCO including the seventhidentification information and/or the TFT and/or the PDN connection ID.

Here, the activated default EPS bearer context request message ID may bea message type representing the activated default EPS bearer contextrequest message.

The APN may be an APN to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection based on theNBIFOM. The MME 40 may include the APN 1 in the activated default EPSbearer context request.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The EPS QoS may be a state representing the EPS bearer QoS.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted/received by using the PDNconnection established in the PDN connectivity procedure is allowed tobe transmitted/received through the access network A and the accessnetwork B, and/or information indicating that the PDN connectionestablished in the present PDN connectivity procedure is themulti-access PDN connection based on the NBIFOM of the operation modeindicated by the seventh identification information.

Note that the UE 10 may transmit the activated default EPS bearercontext request message further including the connectivity type thatindicates the type of the PDN connection and/or the WLAN offloadpermission information (WLAN offload acceptability) indicating whetheror not the WLAN offload can be performed. Furthermore, the MME 40 maytransmit the connectivity type or the WLAN offload permissioninformation including the PDN connection attribute information.

The ESM Cause may be information representing that the PDN type of thePDN address assigned to the UE 10 is different from the PDN typerequested by the UE 10 in the PDN connectivity request.

Note that the MME 40 and/or the PGW 30 may include the seventhidentification information in the PCO. However, when the MME 40 and/orthe PGW 30 includes the seventh identification information in the PCO,the MME 40 and/or the PGW 30 does not include the IFOM support. Incontrast, when the MME 40 and/or the PGW 30 includes the IFOM support inthe PCO, the MME 40 and/or the PGW 30 does not include the seventhidentification information. As described above, it may be possible tonot configure both the seventh identification information and the IFOMsupport to be effective to ensure a clear distinction between the use ofthe switching of the communication path based on the NBIFOM and the useof the switching of the communication path based on the IFOM.

The eNodeB 45 receives the activated default EPS bearer context requesttransmitted from the MME 40. The eNodeB 45 transfers the activateddefault EPS bearer context request to the UE 10, based on the receptionof the activated default EPS bearer context request.

The eNodeB 45 may transmit at least an RRC connection reconfiguration(RRC Connection Reconfiguration) request to the UE 10 along with theactivated default EPS bearer context request (S2416).

The UE 10 receives the RRC connection reconfiguration requesttransmitted from the eNodeB 45. Further, the UE 10 receives theactivated default EPS bearer context request transmitted by the MME 40and then transferred by the eNodeB 45.

Based on the reception of the RRC connection reconfiguration request,the UE 10 transmits an RRC connection reconfiguration complete (RCCConnection Reconfiguration Complete) to the eNodeB 45 (S2418).

The eNodeB 45 receives the RRC connection reconfiguration completetransmitted from the UE 10. The eNodeB 45 transmits a bearerconfiguration to the MME 40 based on the RRC connection reconfigurationcomplete.

The MME 40 receives the bearer configuration transmitted from the eNodeB45 (S2420).

Based on the reception of the activated default EPS bearer contextrequest and/or the seventh identification information included in theactivated default EPS bearer context request, the UE 10 transmits, tothe MME 40, an Activate default EPS bearer context accept or an Activatedefault EPS bearer context reject (S2422) (S2424).

The UE 10 may transmit the Activate default EPS bearer context acceptincluding at least an Activate default EPS bearer context accept messageID (Activate default EPS bearer context accept message identity), theprocedure transaction ID, the protocol discriminator, and the EPS bearerID.

Further, the UE 10 may transmit the Activate default EPS bearer contextreject including at least an Activate default EPS bearer context rejectmessage ID (Activate default EPS bearer context reject messageidentity), the procedure transaction ID, the protocol discriminator, theEPS bearer ID, and the ESM Cause.

Furthermore, the UE 10 may include the PCO in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the Activate default EPS bearercontext accept or the Activate default EPS bearer context reject. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in theactivated default EPS bearer context request, the UE 10 may include theUE-Initiated mode or the Network-Initiated mode in the fifthidentification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

Here, the Activate default EPS bearer context accept message ID may be amessage type representing the Activate default EPS bearer context acceptmessage.

The Activate default EPS bearer context reject message ID may be amessage type representing the Activate default EPS bearer context rejectmessage.

The ESM Cause may be information representing the reason why theactivated default EPS bearer context request is rejected.

With this, the UE 10 transitions to a third initial state (S2310).

In other words, the UE 10, based on having transitioned to the firstinitial state and the Operation mode of the first PDN connection, canestablish a supplemental transfer path through the LTE access network A.

To be specific, the UE 10, based on having transitioned to the firstinitial state and the fact that the first PDN connection is in theNetwork-initiated mode, performs the attach procedure and the PDNconnectivity procedure on the LTE access network A so as to make itpossible to establish the supplemental transfer path through the eNB 45.Note that the transfer path may be a bearer and/or a communication path.

To be more specific, the UE 10 performs the attach procedure toestablish the second PDN connection between the UE 10 and the PGW_Bselected by using the APN 2, and thereafter performs the PDNconnectivity procedure so as to make it possible to add a transfer pathin the first PDN connection between the UE 10 and the PGW_A selected byusing the APN 1 through the LTE access network. Note that the transferpath may be a bearer and/or a communication path.

Alternatively, the UE 10 performs the attach procedure and the PDNconnectivity procedure on the LTE access network A, based on havingtransitioned to the first initial state and the routing rule of thefirst PDN connection in the UE-initiated mode, so as to make it possibleto establish a supplemental transfer path through the eNB 45. Note thatthe transfer path may be a bearer and/or a communication path.

To be specific, the UE 10 performs the attach procedure to establish thesecond PDN connection between the UE 10 and the PGW_B selected by usingthe APN 2, and thereafter performs the PDN connectivity procedure so asto make it possible to add the transfer path in the first PDN connectionbetween the UE 10 and the PGW_A selected by using the APN 1 through theLTE access network. Note that the transfer path may be a bearer and/or acommunication path.

Moreover, the UE 10, based on having transitioned to the second initialstate and the Operation mode of the first PDN connection, can establisha supplemental transfer path through the LTE access network A.

To be specific, the UE 10, based on having transitioned to the secondinitial state and the fact that the first PDN connection is in theNetwork-initiated mode, performs the PDN connectivity procedure on theLTE access network A, thereby making it possible to establish thesupplemental transfer path through the eNB 45. Note that the transferpath may be a bearer and/or a communication path.

To be more specific, the UE 10 performs the PDN connectivity procedureso as to make it possible to add a transfer path in the first PDNconnection between the UE 10 and the PGW_A selected by using the APN 1through the LTE access network. Note that the transfer path may be abearer and/or a communication path.

Alternatively, the UE 10 performs the PDN connectivity procedure on theLTE access network A, based on having transitioned to the second initialstate and the routing rule of the first PDN connection in theUE-initiated mode, so as to make it possible to establish a supplementaltransfer path through the eNB 45. Note that the transfer path may be abearer and/or a communication path.

To be specific, the UE 10 performs the PDN connectivity procedure so asto make it possible to add a transfer path in the first PDN connectionbetween the UE 10 and the PGW_A selected by using the APN 1 through theLTE access network. Note that the transfer path may be a bearer and/or acommunication path.

3. Third Embodiment

A third embodiment in the present invention will be described. The PDNconnection, such as the multi-access PDN connection established by theUE 10 via the TWAG 74 in the first embodiment, is established via theePDG 65.

Note that the mobile communication system and the configuration of eachdevice, such as the UE 10, the PGW 30, and the MME 40, included in themobile communication system in the present embodiment may be similar tothose in the first embodiment, and thus, descriptions thereof will beomitted.

Note that the configuration of the ePDG 65 may be similar to that of theTWAG 74 described with reference to FIG. 3 for the first embodiment.Note that a difference between the ePDG 65 and the TWAG 74 is that theePDG 65 connects the WLAN ANb 75 to the core network 90 whereas the TWAG74 connects the WLAN ANa 70 to the core network 90.

Note that the processes in the ePDG 65 in the present embodiment may besimilar to the processes in the TWAG 74 described for the firstembodiment. The processes in each device such as the UE 10, the PGW 30,the MME 40, and the PCRF 60 may be similar to the processes in eachdevice in the first embodiment.

However, from among the processes of the UE 10 and the PGW 30, theirrespective processes performed for the TWAG 74 will be performed for theePDG 65.

In addition, the PDN connectivity request message described for thefirst embodiment may be a control message in an IKEv2 tunnelestablishment procedure and an IKEv2 authentication request messagetransmitted from the UE 10 to the ePDG 65.

Thus, various information elements included in the IKEv2 authenticationmessage in the present embodiment may be similar to the variousinformation elements included in the PDN connectivity request messagedescribed for the first embodiment. Furthermore, the processes in the UE10 and the ePDG 65 for the transmission/reception of the IKEv2authentication message may be similar to the processes in the UE 10 andthe TWAG 74 for the transmission/reception of the PDN connectivityrequest message described for the first embodiment.

In addition, the PDN Connectivity Accept message described in the firstembodiment may be the control message in the IKEv2 tunnel establishmentprocedure and a permission message for the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Thus, various information elements included in the permission message inthe present embodiment may be similar to the various informationelements included in the PDN Connectivity Accept message described inthe first embodiment. Furthermore, the processes in the UE 10 and theePDG 65 for the transmission/reception of the permission message may besimilar to the processes in the UE 10 and the TWAG 74 for thetransmission/reception of the PDN Connectivity Accept message describedfor the first embodiment.

In addition, the PDN connectivity reject message described for the firstembodiment may be the control message in the IKEv2 tunnel establishmentprocedure and a reject message for the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Thus, various information elements included in the permission message inthe present embodiment may be similar to the various informationelements included in the PDN connectivity reject message described forthe first embodiment. Furthermore, the processes in the UE 10 and theePDG 65 for the transmission/reception of the reject message may besimilar to the processes in the UE 10 and the TWAG 74 for thetransmission/reception of the PDN connectivity reject message describedfor the first embodiment.

This allows the UE 10 to perform communication control for themulti-access PDN connection via the ePDG 65.

4. Fourth Embodiment

A fourth embodiment in the present invention will be described. The PDNconnection, such as the multi-access PDN connection established by theUE 10 via the TWAG 74 in the second embodiment, is established via theePDG 65.

Note that the mobile communication system and the configuration of eachdevice, such as the UE 10, the PGW 30, and the MME 40, included in themobile communication system in the present embodiment may be similar tothose in the second embodiment, and thus, descriptions thereof will beomitted.

Note that the configuration of the ePDG 65 may be similar to that of theTWAG 74 described with reference to FIG. 3 for the second embodiment.Note that a difference between the ePDG 65 and the TWAG 74 is that theePDG 65 connects the WLAN ANb 75 to the core network 90 whereas the TWAG74 connects the WLAN ANa 70 to the core network 90.

Note that the processes in the ePDG 65 in the present embodiment may besimilar to the processes in the TWAG 74 described for the secondembodiment. The processes in each device such as the UE 10, the PGW 30,the MME 40, and the PCRF 60 may be similar to the processes in eachdevice in the second embodiment. However, from among the processes ofthe UE 10 and the PGW 30, their respective processes performed for theTWAG 74 will be performed for the ePDG 65.

In addition, the PDN connectivity request message described for thesecond embodiment may be the control message in the IKEv2 tunnelestablishment procedure and the IKEv2 authentication request messagetransmitted from the UE 10 to the ePDG 65.

Thus, various information elements included in the IKEv2 authenticationmessage in the present embodiment may be similar to the variousinformation elements included in the PDN connectivity request messagedescribed for the second embodiment. Furthermore, the processes in theUE 10 and the ePDG 65 for the transmission/reception of the IKEv2authentication message may be similar to the processes in the UE 10 andthe TWAG 74 for the transmission/reception of the PDN connectivityrequest message described for the second embodiment.

In addition, the PDN Connectivity Accept message described for thesecond embodiment may be the control message in the IKEv2 tunnelestablishment procedure and the permission message for the IKEv2authentication request message transmitted from the ePDG 65 to the UE10.

Thus, various information elements included in the permission message inthe present embodiment may be similar to the various informationelements included in the PDN Connectivity Accept message described forthe second embodiment. Furthermore, the processes in the UE 10 and theePDG 65 for the transmission/reception of the permission message may besimilar to the processes in the UE 10 and the TWAG 74 for thetransmission/reception of the PDN Connectivity Accept message describedfor the second embodiment.

In addition, the PDN connectivity reject message described for thesecond embodiment may be the control message in the IKEv2 tunnelestablishment procedure and the reject message for the IKEv2authentication request message transmitted from the ePDG 65 to the UE10.

Thus, various information elements included in the permission message inthe present embodiment may be similar to the various informationelements included in the PDN connectivity reject message described forthe second embodiment. Furthermore, the processes in the UE 10 and theePDG 65 for the transmission/reception of the reject message may besimilar to the processes in the UE 10 and the TWAG 74 for thetransmission/reception of the PDN connectivity reject message describedfor the second embodiment.

This allows the UE 10 to perform communication control for themulti-access PDN connection via the ePDG 65.

5. Modification

Additionally, the programs run on the devices in the embodiments areeach configured to control a CPU (program causing a computer tofunction) so as to realize the functions of the above-describedembodiments. The information handled by these devices is temporarilyheld in a transitory storage device (RAM, for example) at the time ofprocessing, and is then stored in various storage devices such as a ROMand an HDD, read out by the CPU as necessary, and edited and written.

Here, a semiconductor medium (a ROM, a non-volatile memory card, or thelike, for example), an optical recording medium/magneto-opticalrecording medium (a Digital Versatile Disc (DVD), a Magneto Optical Disc(MO), a Mini Disc (MD), a Compact Disc (CD), a BD, or the like, forexample), a magnetic recording medium (magnetic tape, a flexible disk,or the like, for example), and the like can be given as examples ofrecording media for storing the programs. In addition to realizing thefunctions of the above-described embodiments by executing loadedprograms, the functions of the present invention are realized by theprograms running cooperatively with an operating system, otherapplication programs, or the like in accordance with instructionsincluded in those programs.

When delivering these programs to market, the programs can be stored ina portable recording medium, or transferred to a server computerconnected via a network such as the Internet. In this case, the storagedevice serving as the server computer is of course also included in thepresent invention.

Additionally, each device in the above-described embodiments may bepartially or completely realized as a Large Scale Integration (LSI)circuit, which is a typical integrated circuit. The functional blocks ofeach device may be individually realized as chips, or may be partiallyor completely integrated into a chip. Furthermore, a circuit integrationtechnique is not limited to the LSI, and the integrated circuit may berealized with a dedicated circuit or a general-purpose processor.Furthermore, if advances in semiconductor technology produce circuitintegration technology capable of replacing the LSI, it is of coursepossible to use integrated circuits based on the technology.

Additionally, although, for the above-described embodiments, the LTE andthe WLAN (IEEE 802.11a/b/n, for example) have been descried as examplesof the radio access network, the connections may be made with WiMAXinstead of the WLAN.

REFERENCE SIGNS LIST

-   9 Communication system-   10 UE-   30 PGW-   35 SGW-   40 MME-   45 eNB-   50 HSS-   55 AAA-   60 PCRF-   65 ePDG-   70 WLAN ANa-   74 TWAG-   75 WLAN ANb-   80 LTE AN-   90 Core network-   100 PDN

The invention claimed is:
 1. A User Equipment (UE) comprising: WLAN interface circuitry configured to receive a Packet Data Network (PDN) Connectivity Accept message from a Trusted WLAN Access Gateway (TWAG) in order to establish a first PDN connection; and LTE interface circuitry configured to receive an Activate default EPS bearer context request message from a Mobility Management Entity (MME) in order to establish a second PDN connection, wherein the PDN Connectivity Accept message includes first information indicating a Network-based IP Flow Mobility (NBIFOM) mode, and the Activate default EPS bearer context request message includes second information indicating an NBIFOM mode.
 2. The UE according to claim 1, wherein the first information and the second information indicate a UE-initiated NBIFOM mode or a Network-initiated NBIFOM mode.
 3. The UE according to claim 1, wherein the PDN Connectivity Accept message further includes third information indicating that a request for use of NBIFOM is accepted, and the UE recognizes the first information as an NBIFOM mode for the PDN connection, based on the reception of the PDN Connectivity Accept message. 